One chief objection to this theory is that the lands through which they must have passed are in no way fitted to be an _officina gentium_, being now dry, barren, and all but deserted. But abundant indications remain to show that the climate of South-Eastern Persia and the tracts to the north has changed within comparatively recent times. The relics of crowded populations and ancient civilisations abound in regions now sandy desert, and there is evidence in the tales told by Greek and Chinese travellers that the Panjāb itself, most of it comparatively arid, was once well wooded. The theory then is that the homogeneous and handsome population of the Panjāb and Rājputānā represents the almost pure descendants of Aryan settlers, who carried the Indo-European languages now prevailing over Northern India, just as our own emigrants took the English language to America. But we have also to account for the Aryo-Dravidians who inhabit the sacred "midland" country of Hinduism, and here we have Dr Hoernle's now famous theory, remarkably confirmed by the researches of Sir George Grierson's _Linguistic Survey_. This theory supposes that a second swarm of Aryan-speaking people, perhaps driven forward by the change of climate in central Asia, entered India through the high and difficult passes of Gilgit and Chitral, and established themselves in the fertile plains between the Ganges and the Jumna. They followed a route which made it impossible for their women to accompany them. They took to themselves wives from the daughters of dusky Dravidian aborigines. Here, by contact with a different, and in their sentiment, inferior race, caste came into being. Here most of the Vedic hymns were composed. Here, by a blending of imported and indigenous religious ideals, the ritual and usages of Hindu religion came into being, to spread in altered forms east and west and south. The necessity for this second hypothesis is twofold. It accounts for the marked ethnical barrier which separates western from eastern Hindustan. Elsewhere the various types melt imperceptibly into one another. Here alone is a definite racial border line. Again, the theory accounts for the fact that the Vedic hymns contain no description whatever of the earlier Aryan migration, and for the fact that the inhabitants of the middle land always felt a dislike for the early immigrants as men of low culture and barbarous manners. For the present, at all events, and perhaps for all time, Dr Hoernle's ingenious theory holds the field.