Influences of Geographic Environment Part 37

The possibility of radial expansion, which we have found to be the chief advantage of a central location, is greatly enhanced if that central location coincides with a hydrographic center of low relief. The tenth century nucleus of the Russian Empire was found about the low nodal watershed formed by the Valdai Hills, whence radiated the rivers later embodied in the Muscovite domain. Here In Novgorod at the head of the Volchov-Ladoga-Neva system, Pskof on the Velikaya, Tver at the head of the navigable Volga, Moscow on the Oka, Smolensk on the Dnieper, and Vitebsk on the Duna, were gathered the Russians destined to displace the primitive Finnish population and appropriate the wide plains of eastern Europe. Everywhere their conquests, colonization, and commercial relations have followed the downstream course of their rivers. The Dnieper carried the Rus of Smolensk and Kief to the Euxine, into contact with the Byzantine world, and brought thence religion, art, and architecture for the untutored empire of the north. The influence of the Volga has been irresistible. Down its current Novgorod traders in the twelfth century sought the commerce of the Caspian and the Orient; and later the Muscovite princes pushed their conquest of the Tartar hordes from Asia. The Northern Dwina, Onega, Mesen and Petchora have carried long narrow bands of Slav settlement northward to the Arctic Ocean. [See map page 225.] Medieval Russian trade from Hanseatic Pskof and Novgorod, and later Russian dominion followed the Narva and Neva to the Baltic.

"The Dnieper made Russia Byzantine, the Volga made It Asiatic. It was for the Neva to make it European."[654]

In the same way, when the early French explorers and traders of Canada reached the hydrographic center of the continent about Lakes Superior and Michigan, they quickly crossed the low rim of these basins southward to the Mississippi, and northward to the Rainy Lake and Winnipeg system draining to Hudson Bay.[655] While it took them from 1608 to 1659 and 1662 to penetrate upstream from Quebec to this central watershed, only nine years elapsed from the time (1673) Marquette reached the westward flowing Wisconsin River to 1682, when La Salle reached the mouth of the Mississippi.

[Sidenote: Effect of current upon trade and expansion.]

The effect of mere current upon the course of trade and political expansion was conspicuous in the early history of the Mississippi Valley, before steam navigation began to modify the geographic influence of a river's flow. The wide forest-grown barrier of the Appalachian Mountains placed the western pioneers under the geographic control of the western waters. The bulkiness of their field and forest products, fitted only for water transportation, and the immense ma.s.s of downstream commerce called loudly for a maritime outlet and the acquisition from Spain of some port at the Mississippi mouth. For twenty years the politics of this transmontane country centered about the "Island of New Orleans," and in 1803 saw its dream realized by the Louisiana Purchase.

For the western trader, the Mississippi and Ohio were preeminently downstream paths. Gravity did the work. Only small boats, laden with fine commodities of small bulk and large value, occasionally made the forty day upstream voyage from New Orleans to Louisville. Flat boats and barges that were constructed at Pittsburg for the river traffic were regularly broken up for lumber at downstream points like Louisville and New Orleans; for the traders returned overland by the old Chickasaw Trail to the c.u.mberland and Ohio River settlements, carrying their profits in the form of gold. The same thing happens today, as it also happened two thousand years ago, on the Tigris and Euphrates. The highlander of Armenia or northern Mesopotamia floats down the current in his skin boat or on his brushwood raft, to sell his goods and the wood forming the frame-work of his primitive craft in timberless Bagdad and Busra, as formerly in treeless Babylon. He dries out his skins, loads them on his shoulders or on a mule brought down for the purpose, and returns on foot to his highland village.[656] The same preponderance of downstream traffic appears to-day in eastern Siberia. Pedlers on the Amur start in the spring from Stretensk, 2025 miles up the river, with their wares in barges, and drift down with the current, selling at the villages _en route_, to the river's mouth at Nikolaievsk. Here they dispose of their remaining stock and also of their barges, the lumber of which is utilized for sidewalks, and they themselves return upstream by steamer. The grain barges of western Siberia, like the coal barges of the Mississippi, even within recent decades, are similarly disposed of at the journey's end.[657] The tonnage of downstream traffic on the Ohio and Mississippi to-day greatly exceeds that upstream. The fleet of 56 coal boats, carrying about 70,000 tons, which the great towboat Sprague takes in a single trip from Louisville down to New Orleans, all return empty. Of the 15,226,805 net tons of freight shipped in 1906 on the Ohio system, 13,980,368 tons of coal, stone, sand and lumber were carried in unrigged craft, fitted chiefly for downstream traffic.[658]

[Sidenote: Importance of mouth to upstream people.]

Owing to the strong pull exerted by a river's mouth upon all its basin, current, commerce and people alike tend to reach the ocean. For a nation holding the terrestrial course of a stream, the political fate of its tidal course or mouth must always be a matter of great concern. To the early westerner of the United States, before the acquisition of the Louisiana country, it was of vital importance whether belligerent France or more amenable Spain or the Republic itself should own the mouth of the Mississippi. Germany, which holds 240 miles (400 kilometers) of the navigable Danube,[659] can never be indifferent to the political ownership of its mouth, or to the fact that a great power like Russia has edged forward, by the acquisition of Bessarabia in 1878, to the northern or Kilia debouchment channel.[660] Such interest shows itself in sustained efforts either to gain political control of the mouth, or to secure the neutrality of the stream by having it declared an international waterway, and thus partially to deprive the state holding its mouth of the advantages of its transit location.

The only satisfactory solution is undivided political ownership. After France pushed eastward to the Rhine in 1648, she warred for three centuries to acquire its mouth. Napoleon laid claim to Belgium and Holland on the ground that their soil had been built up by the alluvium of French rivers. Germany's conquest of Schleswig-Holstein in 1864 was significant chiefly because it dislodged Denmark from the right bank of the lower Elbe, and secured undivided control of this important estuary.

The Rhine, which traverses the Empire from north to south and const.i.tutes its greatest single trade route, gives to Germany a more vital interest in Holland than ever France had. Her most important iron and coal mines and manufacturing industries are located on this waterway or its tributaries, the Ruhr, Mosel, Saar and Main. Hence the Rhine is the great artery of German trade and outlet for her enormous exports, which chiefly reach the sea through the ports of Belgium and Holland. These two countries therefore fatten on German commerce and reduce German profits. Hence the Empire, by the construction of the Emden-Dortmund ca.n.a.l, aims to divert its trade from Rotterdam and Antwerp to a German port, and possibly thereby put the screw on Holland to draw her into some kind of a commercial union with Germany.[661]

Heinrich von Treitschke, in his "_Politik_," deplores the fact that the most valuable part of the great German river has fallen into alien hands, and he declares it to be an imperative task of German policy to recover the mouth of that stream, "either by a commercial or political union." "We need the entrance of Holland into our customs union as we need our daily bread."[662]

[Sidenote: Prevention of monopoly of river mouth.]

When the middle and upper course of a river system are shared by several nations, their common interest demands that the control of the mouth be divided, as in the case of the La Plata between Argentine and Uruguay; or held by a small state, like Holland, too weak to force the monopoly of the tidal course. The Treaty of Paris in 1856 extended the territory of Moldavia at the cost of Russia, to keep the Russian frontier away from the Danube.[663] Her very presence was ominous. The temptation to giant powers to gobble up these exquisite morsels of territory is irresistible. Hence the advisability of neutralizing small states holding such locations, as in the case of Roumania; and making their rivers international waterways, as in the case of the Orinoco,[664]

Scheldt, Waal, Rhine and Danube.[665] The Yangtze Kiang mouth, where already the treaty ports cl.u.s.ter thick, will probably be the first part of China to be declared neutral ground, and as such to be placed under the protection of the combined commercial powers,[666] as is even now foreshadowed by the International Conservancy Board of 1910.[667] The United States, by her treaty with Mexico in 1848, secured the right of free navigation on the lower or Mexican course of the Colorado River and the Gulf of California. The Franco-British convention, which in 1898 confirmed the western Sudan to France, also conceded the principle of making the Niger, the sole outlet of this vast and isolated territory, an international waterway, and created two French _enclaves_ in British Nigeria to serve as river ports.[668]

[Sidenote: Motive for ca.n.a.ls in lower course.]

The mouth of a large river system is the converging point of many lines of inland and maritime navigation. The interests of commerce, especially in its earlier periods of development, demand that the contact here of river and sea be extensive as possible. Nature suggests the way to fulfill this requirement. The sluggish lowland current of a river, on approaching sea level, throws out distributaries that reach the coast at various points and form a network of channels, which can be deepened and rendered permanent by ca.n.a.lization. In such regions the opportunity for the improvement and extension of waterways has been utilized from the earliest times. The ancient Egyptians, Chaldeans, East Indians, and the Gauls of the lower Po for thousands of years ca.n.a.led the waters of their deltas and coastal lowlands for the combined purpose of irrigation, drainage, and navigation. The great ca.n.a.l system of China, constructed in the seventh century primarily to facilitate Inland intercourse between the northern and central sections of the Empire, extends from the sea at Hangchow 700 miles northward through the coastal alluvium of the Yangtze Kiang, Hoang-ho and Pie-ho to Tientsin, the port of Peking.

Only the ca.n.a.l system of the center, important both for the irrigation of the fertile but porous loess and for the transportation of crops, is still in repair. Here the meshes of the ca.n.a.l network are little more than half a mile wide; farmers dig ca.n.a.ls to their barns and bring in their produce in barges instead of hay wagons.[669] Holland, where the ancient Romans constructed channels in the Rhine delta and where the debouchment courses of the Rhine, Meuse and Scheldt present a labyrinth of waterways, has to-day 1903 miles (3069 kilometers) of ca.n.a.ls, which together with the navigable rivers, have been important geographic factors in the historical preeminence of Dutch foreign commerce. So on the lower Mississippi, in the greatest alluvial area of the United States, the government has expended large sums for the improvement of the pa.s.ses and bayous of the river. The Barataria, Atchafalaya, Terrebonne, Black, Teche and Lafourche bayous have been rendered navigable, and New Orleans has been given ca.n.a.l outlets to the sea through Lakes Salvador, Pontchartrain and Borgne.

[Sidenote: Watershed ca.n.a.ls.]

As the dividing channels of the lower course point to the feasibility of amplifying the connection with the ocean highway, so the spreading branches of a river's source, which approach other head waters on a low divide, suggest the extension of inland navigation by the union of two such drainage systems through ca.n.a.ls. Where the rivers of a country radiate from a relatively low central watershed, as from the Central Plateau of France and the Valdai Hills of Russia, nature offers conditions for extensive linking of inland waterways. Hence we find a continuous pa.s.sway through Russia from the Caspian Sea to the Baltic by the ca.n.a.l uniting the Volga and Neva rivers; another from the Black Sea up the Dnieper, which by ca.n.a.ls finds three different outlets to the Baltic through the Vistula, Niemen and Duna.[670] The Northern Dwina, linked, by ca.n.a.ls, with the Neva through Lakes Onega and Ladoga, unites the White Sea with the Baltic.[671] Sully, the great minister of Henry IV. of France, saw that the relief of the country would permit the linking of the Loire, Seine, Meuse, Saone and Rhine, and the Mediterranean with the Garonne. All his plans were carried out by his successors, but he himself, at the end of the sixteenth century, began the construction of the Briare Ca.n.a.l between the Loire near Orleans and the Seine at Fontainebleau.[672] Similarly in the eastern half of the United States, the long, low watershed separating the drainage basin of the St. Lawrence and Great Lakes from that of the Mississippi and the Hudson made feasible the succession of ca.n.a.ls completing the "Great Belt" of inland navigation from St. Lawrence and New York bays to the Gulf. Albert Gallatin's famous report of 1808[673] pointed out the adaptation of the three low divides to ca.n.a.l communication; but long before this, every line of possible canoe travel by river and portage over swamp or lake-dotted watershed had been used by savages, white explorers and French voyageurs, from Lake Champlain to Lake Winnebago, so that the ca.n.a.l engineer had only to select from the numerous portage paths already beaten out by the moccasined feet of Indian or fur-trader.

[Sidenote: Rivers and railroads.]

The cheapness and ease of river travel have tended to check or delay the construction of highroads and railways, where facilities for inland navigation have been abundant, and later to regulate railway freight charges. Conversely, riverless lands have everywhere experienced an exaggerated and precocious railroad development, and have suffered from its monopoly of transportation. Even ca.n.a.ls have in most lands had a far earlier date than paved highroads. This has been true of Spain, France, Holland, and England.[674] In the Hoang-ho Valley of northern China where waterways are restricted, owing to the rapid current and shallowness of this river, highroads are comparatively common; but they are very rare in central and southern China where navigable rivers and ca.n.a.ls abound.[675] New England, owing to its lack of inland navigation, was the first part of the United States to develop a complete system of turnpikes and later of railroads. On the other hand, the great river valleys of America have generally slighted the highroad phase of communication, and slowly pa.s.sed to that of railroads. The abundance of natural waterways in Russia--51,800 miles including ca.n.a.ls--has contributed to the r.e.t.a.r.dation of railroad construction.[676] The same thing is true in the Netherlands, where 4875 miles (7863 kilometers) of navigable waterways[677] in an area of only 12,870 square miles (33,000 square kilometers) have kept the railroads down to a paltry 1818 miles (2931 kilometers); but smaller Belgium, commanding only 1375 miles (3314 kilometers) of waterway and stimulated further by a remarkable industrial and commercial development, has constructed 4228 miles (6819 kilometers) of railroad.

[Sidenote: Relation of rivers to railroads in recent colonial lands.]

If we compare the countries of Central and South America, where railroads are still mere adjuncts of river and coastwise routes, a stage of development prevalent in the United States till 1858, we find an unmistakable relation between navigable waterways and railroad mileage.

The countries with ample or considerable river communication, like Brazil, Venezuela, Colombia and Paraguay, are all relatively slow in laying railroads as compared with Mexico and Argentine, even when allowance is made for differences of zonal location, economic development, and degree of European elements in their respective populations. Mexico and Argentine, having each an area only about one-fourth that of Brazil but a railroad mileage nearly one-fourth greater, have been pushed to this development primarily by a common lack of inland navigation. Similarly South Africa, stricken with poverty of water communication south of the Zambesi, has constructed 7500 miles of railroads[678] in spite of the youth of the country and the sparsity of its white population. Similar geographic conditions have forced the mileage of Australian railways up to twice that of South Africa, in a country which is still in the pastoral and agricultural stage of development, and whose most densely populated province Victoria has only fourteen inhabitants to the square mile. In the almost unpeopled wastes of Trans-Caspia, where two decades ago the camel was the only carrier, the Russian railroad has worked a commercial revolution by stimulating production and affording an outlet for the irrigated districts of the encircling mountains.[679] In our own Trans-Missouri country, where the scanty volume of the streams eliminated all but the Missouri itself as a dependable waterway, even for the canoe travel of the early western trappers, railroads have developed unchecked by the compet.i.tion of river transportation.[680] With no rival nearer than the Straits of Magellan and the Isthmus of Panama for transportation between the Mississippi and the Pacific coast, they have fixed their own charges on a monopoly basis, and have fought the construction of the Isthmian Ca.n.a.l.

[Sidenote: Unity of a river system.]

A river system is a system of communication. It therefore makes a bond of union between the people living among its remoter sources and those settled at its mouth. Every such river system forms geographically an unbroken whole. Only where a wild, torrent-filled gorge, like the Brahmaputra's path through the Himalayas, interrupts communication between the upper and lower course, is human life in the two sections divorced. But such cases are rare. Even the River Jhelam, which springs with mad bounds from the lofty Vale of Kashmir through the outer range of the Himalayas down to its junction with the Indus, carries quant.i.ties of small logs to be used as railway sleepers; and though it shatters a large per cent. of them, it makes a link between the lumber men of the Kashmir forests and British railroad engineers in the treeless plains of the Indus.[681]

[Sidenote: The effect of common water supply in arid lands.]

In arid lands, where the scant and variable streams are useless for navigation, but invaluable for irrigation, a rival interest in the limited water supply leads almost inevitably to conflict, and often to the political union of the peoples holding the upper and lower courses, in order to secure adjustment of their respective claims. The ancient Sala.s.si of the upper Doria Baltea Valley in the Alps drew off all the water of the stream for washing gold, and thus deprived the agricultural people lower down the valley of the water necessary for irrigation. The result was frequent wars between the two tribes.[682] The offensive is taken by the downstream people, whose fields and gardens suffer from every extension of tillage or increase of population in the settlements above them. Occasionally a formal agreement is a temporary expedient.

The River Firenze and other streams watering southern Trans-Caspia have their sources in the mountains of northern Persia; hence the Russians, in the boundary convention with Persia of 1881, stipulated that no new settlement be established along these streams within Persian territory, no extension of land under cultivation beyond the present amount, and no eduction of the water beyond that necessary to irrigate the existing fields.[683] Russia's designs upon Afghanistan aim not only at access to India, but also at the control of the upper Murghab River, on whose water depends the prosperity of the Pendjeh and Merv oases.[684] In such regions the only logical course is the extension of the political frontier to the watershed, a principle which Russia is applying in western Asia, and which California applied in drawing her eastern boundary to include even Goose Lake.

[Sidenote: Union of opposite river banks.]

Rivers unite. Ancient Rome grew up on both banks of the Tiber, and extended her commercial and political supremacy up and down stream. Both sides of the Rhine were originally occupied by the Gallic tribes, whose villages were in some instances bisected by the river. Caesar found the Menapii, a Belgian people on the lower Rhine, with their fields, farmhouses and villages on both banks.[685] Then the westward advance of the Teutonic tribes gradually transformed the Rhine into a German river, from the island of Batavia at its mouth up to the great elbow at the foot of the Jura Mountains.[686] To the American Indians even the widest rivers were no barriers. Christopher Gist, exploring the Ohio in 1751, found a Shawnee village situated on both sides of the river below the mouth of the Scioto, with about a hundred houses on the north bank and forty on the south.[687] The small and unique nation of the Mandan Indians were found by Lewis and Clark near the northern bend of the Missouri in 1804, in two groups of villages on opposite sides of the river. They had previously in 1772 occupied nine villages lower down the stream, two on the east bank and seven on the west.[688] The Connecticut River settlers of early colonial days laid out all their towns straight across the valley, utilizing the alluvial meadows on both banks for tillage, the terraces for residence sites, and the common river for intercourse.[689]

[Sidenote: Tendency toward ethnic and cultural unity in a river valley.]

Every river tends to become a common artery feeding all the life of its basin, and gradually obliterating ethnic and cultural differences among the peoples of its valley. The Nile, with its narrow hem of flood-plain on either bank and barrier sands beyond, has so linked race and history in Egypt and Nubia, that the two countries cannot be separated. A common highway from mountains to sea, a common frontier of trackless desert have developed here a blended similarity of race, language and culture from the delta to Kordofan. The Hamitic race seems to have originated in the south and migrated northward down the Nile towards the delta. Later the whole valley, north and south, received the same Semitic or Arab immigration, which spread from Cairo to the old Sudanese capital of Sennar, while a strain of negro blood has filtered in from the equatorial black belt and followed the current down to the sea.[690] The culture of the valley originated in Lower Egypt, and, with that easy transmissibility which characterizes ideas, it moved upstream into Ethiopia, which never evolved a culture of its own. Just as noticeable is the political interplay. The rule of the Pharaohs extended far up the Nile, at times to the Third Cataract at 20 N.L.; and at one period Ethiopian kings extended their sway over Egypt. At another, a large body of mutinous Egyptian soldiers abandoned their country and their wives, and emigrated along the one line of slight resistance open to them into Ethiopia, to found there a new state and new families by marriage with native women, thus contributing to the amalgamation of races in the valley.

[Sidenote: Ident.i.ty of country with river valley.]

The most p.r.o.nounced types of the ident.i.ty of a country with a river valley are found where strongly marked geographical boundaries, like deserts and mountains, emphasize the inner unity of the basins by accentuating their isolation from without. This is especially the case in high mountain regions; here canton or commune or county coincides with the river valley. Population hugs the margins of the streams where alone is soil fit for cultivation, and fairly level land suitable for dwellings. Above are the unoccupied heights, at once barrier and boundary. In the Alps, Salzburg is approximately identical with the valley of the Salzach, Uri with that of the Reuss, the Valais with the upper Rhone, the Engadine with the upper Inn, Glarus with the Linth, Graubunden or Grisons with the upper Rhine, Valtellina with the Adda. So in the great upheaved area of the Himalayas, the state of Kashmir was originally the valley of the upper Jhelam River, while a.s.sam, in its correct delimitation, is the valley of the Brahmaputra between the Himalayan gorge and the swamps of Bengal.[691]

In mountain regions which are also arid, the ident.i.ty of a district with a stream basin becomes yet more p.r.o.nounced, because here population must gather about the common water supply, must organize to secure its fair distribution, and cooperate in the construction of irrigation channels to make the distribution as economical and effective as possible. Thus in Chinese Turkestan, the districts of Yarkand, Kashgar, Aksu and Kut-sha are identical with as many mountain tributaries of the Tarim, whose basin in turn comprises almost the whole of Chinese Turkestan.

[Sidenote: Enclosed river valleys.]

In all such desert and mountain-rimmed valleys, the central stream attracts to its narrow hem of alluvial soil the majority of the population, determines the course of the main highroad, and is itself often the only route through the encompa.s.sing barriers. Hence the importance attached to the river by the inhabitants, an importance reflected in the fact that the river often gives its name to the whole district. To the most ancient Greeks _Aigiptos_ meant the river, whose name was later transferred to the whole land; for the narrow arable strip which const.i.tuted Egypt was "the gift of the Nile." The Aryans, descending into India through the mountains on its northwest border, gave the name of _Sindhu_, "the flood" or "the ocean," to the first great river they met. In the mouth of Persians and Greeks the name was corrupted into Indus, and then applied to the whole country; but it still survives in its original form in the local designation of the Sind province, which comprises the valley of the Indus below the confluence of the five rivers, which again formed and named the original Punjab.

Significantly enough the western political boundary of the Sind extends into the barren foothills of Baluchistan only so far as the affluents of the Indus render the land arable by irrigation; for the Indus performs for the great province of the Sind, by annual inundation and perennial irrigation, the same service that the Nile does for Egypt.

The segregation of such districts, and the concentration of their interests and activities along the central streams have tended to develop in the population an intense but contracted national consciousness, and to lend them a distinctive history. Their rivers become interwoven with their mythology and religion, are G.o.ds to be worshipped or appeased, become goals of pilgrimages, or acquire a peculiar sanct.i.ty. The Nile, Ganges, Jamna, Jordan, Tiber and Po are such sacred streams, while the Rhine figures in German mythology.

[Sidenote: Rivers as boundaries of races and peoples.]

From the uniting power of rivers it follows that they are poor boundaries. Only mountains and seas divide sharply enough to form scientific frontiers. Rivers may serve as political lines of demarcation and therefore fix political frontiers; but they can never take the place of natural boundaries. A migrating or expanding people tend always to occupy both slopes of a river valley. They run their boundary of race or language across the axis of their river basin, only under exceptional circ.u.mstances along the stream itself. The English-French boundary in the St. Lawrence Valley crosses the river in a broad transitional zone of mingled people and speech in and above the city of Montreal. The French-German linguistic frontier in Switzerland crosses the upper Rhone Valley just above Sierre, but the whole canton of Valais above the elbow of the river at Martigny shows fundamental ethnic unity, indicated by ident.i.ty of head form, stature and coloring.[692] Where the Elbe flows through the low plains of North Germany, its whole broad valley is occupied by a pure Teutonic population--fair, tall, long-headed; a more brunette type occupies its middle course across the uplands of Saxony, and speaks German like the downstream folk; but its upper course, hemmed in by the Erz and Riesen Mountains, shows the short, dark and broad-headed people of the Bohemian basin, speaking the Czech language.[693] On the Danube, too, the same thing is true. The upper stream is German in language and predominantly Alpine in race stock down to the Austro-Hungarian boundary; from this point to the Drave mouth it is Hungarian; and from the Drave to the Iron Gate it is Serbo-Croatian on both banks.[694] Lines of ethnic demarcation, therefore, cut the Elbe and Danube transversely, not longitudinally. [See map page 223.]

The statements of Caesar and Pliny that the Seine and Marne formed the boundary between the Gauls and Belgians, and the Garonne that between the Gauls and Aquitanians, must be accepted merely as general and preliminary; for exceptions are noted later in the text. Parisii, for instance, were represented as holding both banks of the Seine and Marne at their confluence, and the Gallic Bituriges were found on the Aquitanian side of the Garonne estuary.

[Sidenote: Scientific river boundaries.]

Only under peculiar conditions do rivers become effective as ethnic, tribal or political boundaries. Most often it is some physiographic feature which makes the stream an obstacle to communication, and lends it the character of a scientific boundary. The division of the Alpine foreland of southern Germany first into tribal and later into political provinces by the Iller, Lech, Inn, and Salzach can be ascribed in part to the tumultuous course of these streams from the mountains to the Danube, which renders them useless for communication.[695] The lower Danube forms a well maintained linguistic boundary between the Bulgarians and Roumanians, except in the northwest corner of Bulgaria, where the hill country between the Timok River and the Danube has enticed a small group of Roumanians across to the southern side. From this point down the stream, a long stretch of low marshy bank on the northern side, offering village sites only at the few places where the loess terrace of Roumania comes close to the river, exposed to overflows, strewn with swamps and lakes, and generally unfit for settlement, has made the Danube an effective barrier.[696] Similarly, the broad, sluggish Shannon River, which spreads out to lake breadth at close intervals in its course across the boggy central plain of Ireland, has from the earliest times proved a sufficient barrier to divide the plain into two portions, Connaught and Meath,[697] contrasted in history, in speech and to some extent even in race elements.[698] A different cause gave the Thames its unique role among the larger English rivers as a boundary between counties from source to mouth. London's fortified position at the head of the Thames estuary closed this stream as a line of invasion to the early Saxons, and forced them to make detours to the north and south of the river, which therefore became a tribal boundary.[699]

Where navigation is peculiarly backward, a river may present a barrier.

An instructive instance is afforded by the River Yo, which flows eastward through northern Bornu into Lake Chad, and serves at once as boundary and protection to the agricultural tribes of the Kanuri against the depredations of the Tibbu robbers living in the Sahara or the northern gra.s.sland. But during the dry season from April to August, when the trickling stream is sucked up by the thirsty land and thirstier air, the Tibbu hors.e.m.e.n sweep down on the unprotected Kanuri and retreat with their booty across the vanished barrier. The primitive navigation by reed or brushwood rafts, practiced in this almost streamless district, affords no means of retreat for mounted robbers; so the raiding season opens with the fall of the river.[700]

[Sidenote: Rivers as political boundaries.]

For political boundaries, which are often adopted with little reference to race distribution, rivers serve fairly well. They are convenient lines of demarcation and strategic lines of defense, as is proved by the military history of the Rhine, Danube, Ebro, Po, and countless other streams. On the lower Zambesi Livingstone found the territories of the lesser chiefs defined by the rivulets draining into the main river. The leader of the Makololo formally adopted the Zambesi as his political and military frontier, though his people spread and settled beyond the river.[701] Long established political frontiers may become ethnic boundaries, more or less distinct, because of protracted political exclusion. To the Romans, the Danube and Rhine as a northeastern frontier had the value chiefly of established lines in an imperfectly explored wilderness, and of strategic positions for the defense of an oft a.s.sailed border; but the long maintenance of this political frontier resulted in the partial segregation and hence differentiation of the people dwelling on the opposite banks.

Poor as a scientific boundary, a river is not satisfactory even as a line of demarcation, because of its tendency to shift its bed in every level stretch of its course. A political boundary that follows a river, therefore, is often doomed to frequent surveys. The plantations on the meanders of the lower Mississippi are connected now with one, now with the other of the contiguous states, as the great stream straightens its course after the almost annual overflow.[702] The Rio Grande has proved a troublesome and expensive boundary between the United States and Mexico. Almost every rise sees it cutting a new channel for itself, now through Texas, now through Mexican territory, occasioning endless controversies as to the ownership of the detached land, and demanding fresh surveys. Recent changes in the lower course of the Helmund between Nasralabad and the Sistan Swamp, which was adopted in 1872 as the boundary between Afghanistan and Persia, have necessitated a new demarcation of the frontier; and on this task a commission is at present engaged.[703] In a like manner Strabo tells us that the River Achelous, forming the boundary between ancient Acarnania and Aetolia in western h.e.l.las, by overflowing its delta region, constantly obliterated the boundaries agreed upon by the two neighbors, and thereby gave rise to disputes that were only settled by force of arms.[704]

[Sidenote: Fluvial settlements and peoples.]

Rivers tend always to be centers of population, not outskirts or perimeters. They offer advantages that have always attracted settlement--fertile alluvial soil, a nearby water supply, command of a natural highway for intercourse with neighbors and access to markets.

Among civilized peoples fluvial settlements have been the nuclei of broad states, pa.s.sing rapidly through an embryonic development to a maturity in which the old center can still be distinguished by a greater density of population. Only among savages or among civilized people who have temporarily reverted to primitive conditions in virgin colonial lands, do we find genuine riverine folk, whose existence is closely restricted to their bordering streams. The river tribes of the Congo occupy the banks or the larger islands, while the land only three or four miles back from the stream is held by different tribes with whom the riverine people trade their fish. The latter are expert fishermen and navigators, and good agriculturists, raising a variety of fruits and vegetables. On the river banks at regular intervals are market greens, neutral ground, whither people come from up and down stream and from the interior to trade. Their long riparian villages consist of a single street, thirty feet wide and often two miles long, on which face perhaps three hundred long houses,[705] Fisher and canoe people line the Welle, the great northern tributary of the Congo.[706] The same type appeared in South America in the aboriginal Caribs and Tupis dwelling along the southern tributaries of the Amazon and the affluents of the Paraguay.

These were distinctly a water race, having achieved a meager development only in navigation, fishing and the cultivation of their alluvial soil.[707] The ancient mound-builders of America located their villages chiefly, though not exclusively, along the princ.i.p.al watercourses, like the Mississippi, Illinois, Miami, Wabash, Wisconsin, and Fox,[708] on the very streams later dotted by the trading posts of the French voyageurs.

[Sidenote: Riparian villages of French Canada.]