From the valley of the Dniester to the basin of the Theiss the steppes of southern Russia spread in unvarying uniformity save where the tableland of the Transylvanian Alps breaks their continuity. The entire region was the Dacia colonized by the Romans.[167] Unity of life, in this home of Rumanian nationality, has been unaffected by the sharp physical diversity afforded by the inclosure of mountain and plain within the same linguistic boundary. The thoroughness with which Rumanians have adapted themselves to the peculiarities of their land is evinced by the combination of the twin occupations of herder and husbandman characteristic of Moldavians and Wallachians. Cattle and flocks are led every summer to the rich grazing lands of the Transylvania valleys. In winter man and beast seek the pastures of the Danubian steppes and prairies. Rumanians thus maintain mountain and plain residences, which they occupy alternately.[168] This mode of life is the transformation which the nomadism of the Asiatic steppe received on Rumanian soil. It is a true relic of past habitat. These seasonal migrations also account for the intimacy between highlanders and lowlanders in Rumania, besides affording adequate explanation of the peopling of the region by a single nationality.[169] There was a time, however, when Rumanian nationality was entirely confined to the mountain zone. Invasions which followed the retirement of the Romans had driven Rumanians to the shelter of the Transylvanian ranges. Perched on this natural fortress, they beheld the irruption of Slavs and Tatars in the broad valleys which they once held in undisputed sway. Only after the flow of southeastern migrations had abated did they venture to reoccupy the plains and resume their agricultural life and seasonal wanderings. The outstanding fact in these historical vicissitudes is that the mountain saved the Latin character of Rumanian speech. Had the Romanized Dacians been unable to find refuge in the Transylvanian Alps their language would probably have been submerged by the Slavic or Tatar flood. As it is, the life of Rumanians is strongly impregnated with eastern influences. Oddly enough its Christianity was derived from Byzantium instead of from Rome and, were it not for a veritable renaissance of Latinism about 1860, its affinity with the Slavic world would be manifest with greater intensity than is apparent in the present century.