One element the two peoples certainly had in common--a highly developed agricultural system, which formed the foundation of their greatness, and was maintained in a rainless climate by a stupendous system of irrigation works. Such works were carried out on a prodigious scale by the ancient Babylonians six or eight thousand years ago. The plains of the Lower Euphrates and Tigris, since rendered desolate under Turkish misrule, are intersected by the remains of an intricate network of canalisation covering all the space between the two rivers, and are strewn with the ruins of many great cities, whose inhabitants, numbering scores of thousands, were supported by the produce of a highly cultivated region, which is now an arid waste varied only by crumbling mounds, stagnant waters, and the camping-grounds of a few Arab tent-dwellers. * * * * * Those who attach weight to distinctive racial qualities have always found a difficulty in attributing this wonderful civilisation to the same Mongolic people, who in their own homes have scarcely anywhere advanced beyond the hunting, fishing, or pastoral states. But it has always to be remembered that man, like all other zoological forms, necessarily reflects the character of his environment. The Mongols might in time become agriculturalists in the alluvial Mesopotamian lands, though the kindred people who give their name to the whole ethnical division and present its physical characters in an exaggerated form, ever remain tented nomads on the dry Central Asiatic steppe, which yields little but herbage, and is suitable for tillage only in a few more favoured districts. Here the typical Mongols, cut off from the arable lands of South Siberia by the Tian-shan and Altai ranges, and to some extent denied access to the rich fluvial valleys of the Middle Kingdom by the barrier of the Great Wall, have for ages led a pastoral life in the inhabitable tracts and oases of the Gobi wilderness and the Ordos region within the great bend of the Hoang-ho. During the historic period these natural and artificial ramparts have been several times surmounted by fierce Mongol hordes, pouring like irresistible flood-waters over the whole of China and many parts of Siberia, and extending their predatory or conquering expeditions across the more open northern plains westwards nearly to the shores of the Atlantic. But such devastating torrents, which at intervals convulsed and caused dislocations amongst half the settled populations of the globe, had little effect on the tribal groups that remained behind. These continued and continue to occupy the original camping-grounds, as changeless and uniform in their physical appearance, mental characters, and social usages as the Arab bedouins and all other inhabitants of monotonous undiversified steppe lands.