Various, Encyclopaedia Britannica, 11th Edition…
“ Here we propose to offer a brief review of the special course of their development in India.Most of the Indo-Aryans branched off from the common Aryan stock in the highlands of Khokand and Badakshan, and marched south into what is now eastern Afghanistan. Here some of them settled, while others entered the Punjab by the valley of the river Kabul. This last migration was a gradual process extending over several centuries, and at different epochs different tribes came in, speaking different dialects of the common language. ”
