For these and other reasons, domestic slavery under the Persian rule, although sheltered by political servitude, had but small growth and made but slow progress. It certainly did not desolate the lands with the blight and barrenness that afterward depopulated them under Roman rule. The tribute paid by the subdued nations to the Persian kings and their court, included slaves--boys and girls--but in a limited number. The slave-traffic existed as of old; but, in all probability, the supply of the human merchandise was less plentiful. From political slaves, but not domestic chattels, it was that the armies were recruited which crossed the Hellespont and invaded Greece. But, viewing the matter in the gross and scope of historical development, political slavery and the blighting effects of the oppressive despotism to which the Persians were long subjected, may be looked upon as the soil out of which grew the morbid and monstrous system of domestic slavery, just as external influences frequently develop and foster the germs of a chronic and fatal bodily disease. IX. ARYAS--HINDUS. AUTHORITIES: _Lassen, Wilson, Weber, Max Müller, Pictet, Kuhn, etc._ The central region of Baktria was in all probability the cradle of the Aryas, the common progenitors of all the races and nations which now cover Europe. In times anterior to the great pre-historic division and separation of the Aryan races, they probably occupied the whole of the vast region stretching from the Hindu-Kush, the Belourtagh, to the river Oxus and the Caspian Sea. This, too, at a period of which it can only be said that time existed. The antique Aryas led a pastoral life. The original signification of the words in the European languages denoting family and social relations, as well as the names of domestic and other animals, of grains and plants, of implements of husbandry and handicraft and the like, is elucidated by roots found in Sanscrit, which is supposed to have been the original language of the Aryas, or, at any rate, the one which most completely preserved the primitive impress of the Aryan character.