Note 1213 — Chapter XV · —Mountain Barriers And Their Passes

In their valleys, mountains lose something of their barrier nature, and approximate the level of the plains. Here they harbor oases of denser population and easier intercourse. Valleys favor human settlement through the milder climate of their lower elevation, the accumulation of soil on their floors, their sheltered environment, and their command of such routes of communication as the highlands afford. They are the avenues into and within a mountain system, and therefore radically influence its history by their direction and location. The Central Plateau of France, through the valleys of the Alliers and upper Loire, is most accessible from the north; therefore in that direction it has maintained its most important historical connections,1213 from the days of Cæsar and Vercingetorix. The massive highland region of Transylvania, which opens long accessible valleys westward toward the plains of the Theiss and Danube, has since the eleventh century received thence Hungarian immigration and political dominion.1214 Its dominant Roumanian population, however, seems to have fled thither from the Tartar-swept plains to the southeast.