It is agreed that Harappan civilization declined around 1700B.C and Indo-Aryans began to appear on Indian Horizons about 1500B.C. So it is ruled out that IVC was destroyed by the invading Aryan tribes. There are numerous theories like, earthquakes, famines for the decline of IVC. Few historians do not rule out invasions by barbarian tribes of north-west.
But I found nobody has taken into account two important factors.
1. Melanin pigmentation distribution among population
2. Behavioural outlook of the people.
These two factors will be discussed in the succeeding paragraphs.
1. Melanin pigmentation:
If we observe present day population of Indian sub-continent the skin pigmentation increases as you move from north-west( present day
The main occupation of Harappan people was trading. And present day Harappan tract population of Sindhis , Gujaratis and Rajasthani Marwaris are still predominantly trading communities.
The dark skinned population of