In the first place, no migration is ever simple; it involves a number of secondary movements, each of which in turn occasions a new combination of tribal or racial elements. The transference of a whole people from its native or adopted seat to a new habitat, as in the Völkerwanderungen, empties the original district, which then becomes a catchment basin for various streams of people about its rim; and in the new territory it dislodges a few or all of the occupants, and thereby starts up a fresh movement as the original one comes to rest.
Nor is this all. A torrent that issues from its source in the mountains is not the river which reaches the sea. On its long journey from highland to lowland it receives now the milky waters of a glacier-fed stream, now a muddy tributary from agricultural lands, now the clear waters from a limestone plateau, while all the time its racing current bears a burden of soil torn from its own banks. Now it rests in a lake, where it lays down its weight of silt, then goes on, perhaps across an arid stretch where its water is sucked up by the thirsty air or diverted to irrigate fields of grain. So with those rivers of men which we call migrations. The ethnic stream may start comparatively pure, but it becomes mixed on the way. From time to time it leaves behind laggard elements which in turn make a new racial blend where they stop. Such were the six thousand Aduatici whom Cæsar found in Belgian Gaul. These were a detachment of the migrating Cimbri, left there in charge of surplus cattle and baggage while the main body went on to Italy.[142]
Complex currents of migration.
A migration rarely involves a single people even at the start. It becomes contagious either by example or by the subjection of several neighboring tribes to the same impelling force, by reason of which all start at or near the same time. We find the Cimbri and Teutons combined with Celts from the island of Batavia[143] in the first Germanic invasion of the Roman Empire. Jutes, Saxons and Angles started in close succession for Britain, and the Saxon group included Frisians.[144] An unavoidable concomitant of great migrations, especially those of nomads, is their tendency to sweep into the vortex of their movement any people whom they brush on the way. Both individuals and tribes are thus caught up by the current. The general convergence of the central German tribes towards the Danube frontier of the Roman Empire during the Marcomannic War drew in its train the Lombards from the lower Elbe down to the middle Danube and Theiss.[145] The force of the Lombards invading Italy in 568 included twenty thousand Saxons from Swabia, Gepidae from the middle Danube, Bulgarians, Slavs from the Russian Ukraine, together with various tribes from the Alpine district of Noricum and the fluvial plains of Pannonia. Two centuries later the names of these non-Lombard tribes still survived in certain villages of Italy which had formed their centers.[146] The army which Attila the Hun brought into Gaul was a motley crowd, comprising peoples of probable Slav origin from the Russian steppes, Teutonic Ostrogoths and Gepidae, and numerous German tribes, besides the Huns themselves. When this horde withdrew after the death of Attila, Gepidae and Ostrogoths settled along the middle Danube, and the Slavonic contingent along the Alpine courses of the Drave and Save Rivers.[147] The Vandal migration which in 409 invaded Spain included the Turanian Alans and the German Suevi. The Alans found a temporary home in Portugal, which they later abandoned to join the Vandal invasion of North Africa, while the Suevi settled permanently in the northwestern mountains of Spain. The Vandals occupied in Spain two widely separated districts, one in the mountain region of Galicia next to the Suevi, and the other in the fertile valley of Andalusia in the south, while the northeastern part of the peninsula was occupied by intruding Visigoths.[148] Add to these the original Iberian and Celtic stocks of the peninsula and the Roman strain previously introduced, and the various elements which have entered into the Spanish people become apparent.[149]
Cultural modification during migration.
The absorption of foreign elements is not confined to large groups whose names come down in history, nor is the ensuing modification one of blood alone. Every land migration or expansion of a people passes by or through the territories of other peoples; by these it is inevitably influenced in point of civilization, and from them individuals are absorbed into the wandering throng by marriage or adoption, or a score of ways. This assimilation of blood and local culture is facilitated by the fact that the vast majority of historical movements are slow, a leisurely drift. Even the great Völkerwanderung, which history has shown us generally in the moment of swift, final descent upon the imperial city, in reality consisted of a succession of advances with long halts between. The Vandals, whose original seats were probably in central or eastern Prussia, drifted southward with the general movement of the German barbarians toward the borders of the Empire late in the second century, and, after the Marcomannic War (175 A.D.), settled in Dacia north of the lower Danube under the Roman sway. In 271 they were located on the middle Danube, and sixty years afterwards in Moravia. Later they settled for seventy years in Pannonia within the Empire, where they assimilated Roman civilization and adopted the Arian form of Christianity from their Gothic neighbors.[150] In Spain, as we have seen, they occupied Galicia and Andalusia for a time before passing over into Africa in 429. Here was a migration lasting two centuries and a half, reaching from the Baltic to the southern shores of the Mediterranean, starting on the bleak sterile plains of the north amid barbarous neighbors, ending in the sunny grain fields and rich cities of Roman Africa. The picture which we get of the victorious Vandals parceling out the estates of Roman nobles, and, from the standpoint of their more liberal faith, profiting by the dissensions of the two Catholic sects of Africa, shows us a people greatly modified by their long sweep through the civilized outskirts of the Empire. So it was with the Lombards and Goths who invaded Italy.
Among primitive tribes, who move in smaller groups and must conform closely to the dictates of their environment, the modifying effects of people and land through which they pass are conspicuous. Ratzel describes the gradual withdrawal of a Hottentot people from western Cape Colony far into the arid interior before the advance of Kaffirs and Europeans by saying: "The stock and name of the Namaquas wandered northward, acquiring new elements, and in course of time filling the old mold with new contents."[151] This is the typical result of such primitive movements. The migration of the Delaware Indians from an early home somewhere northwest of the Great Lakes to their historical habitat between the Hudson and Potomac Rivers was a slow progress, which somewhere brought them into contact with maize-growing tribes, and gave them their start in agriculture.[152] The transit lands through which these great race journeys pass exercise a modifying effect chiefly through their culture and their peoples, less through their physical features and climate. For that the stay of the visitants is generally too brief.