Conditions hardly more favorable belong to the extreme northern portion of the great plain of Europe, the slope of which is directed toward the White Sea and the Arctic basin. But a large portion of Eastern Europe is inclined toward a southerly sky, and is watered by rivers which have their outfall into the Black and Caspian Seas. The Volga, the longest of European rivers, belongs to the Caspian basin, the most depressed portion of the entire region. The southeastern division of the European lowland, and the adjacent portions of Asia, constitute the region of the _steppes_. These occupy an immense portion of the empire of Russia, and are among the most characteristic of the physical features of the Old World. The steppes are grassy plains--prairies, or meadows, they would be called in the New World--which occupy a vast belt of the European and Asiatic continents. They stretch eastward from the banks of the Dnieper far into the heart of Asia--along the shores of the Caspian and Aral Seas, and as far as the banks of the great river Obi. Indeed, in so far as their grassy covering and general level expanse--among the prime characteristics of the steppe-land--are concerned, a like region may be said to extend to the eastward through Central Asia, as far as the Great Wall of China and the valley of the Amour. This is the “land of grass” of the Mongol shepherd, the true home of the Tartar nations, whose descendants yet preserve in their songs the memory of their famous leader Timour--the Tamerlane of historic record. So vast is the extent of this grass-covered region, that a mounted horseman, it has been said, setting out from one of its extremities at the beginning of the year, and traveling day and night at his utmost speed, would find the season of spring elapse ere he reached its further limits.