Tradition or myth… directly indicates that the Ailas (or Aryans) entered India from the mid-Himalayan region. - Frederick Eden Pargiter

The bulk of the Rigveda was composed in the great development of Brahmanism that arose under the succesors of king Bharata who reigned in the upper Ganges-Jumna doab and plain;

Indian tradition distinctly asserts that there was an Aila outflow of the Druhyus through the northwest into the countries beyond where they founded various kingdoms.

There is a strong presumption in favor of (Indian) tradition; if anyone contests tradition, the burden lies on him to show that it is wrong.