The area covered by Harappan civilization was bigger than ancient Egypt and Mesopotamia combined  and there are various model which try to explain how the land was administered. One model suggests that it was not centrally governed, but had  various domains centered around five major cities. While Mohenjo-daro and Harappa are the most well known sites of the Indus-Saraswati civilization, Rakhigarhi in Haryana, which was probably one of those capital cities, is less known. Located on the dry river bed of Saraswati, apsidal structures and fire altars too have been discovered there.
In an interview with Sunday Guardian, Vasant Shinde, Professor of Archaeology at Deccan College talks about Rakhigarhi and the question of Aryan invasion/migration.

Has Rakhigarhi been able to shed any light on the theory of the origin and history of Aryans?
It is an intriguing question, one that can be understood only by identifying the actual cultural sequence of the Ghaggar/Saraswati. There are different hypotheses as regards the identity of the people who thrived on the banks of the Saraswati. Some people believe these were Aryans while others insist they were non-Aryans. My argument is that from 7000 BC onwards, we don’t have any evidence of people migrating. If we say the Aryans came from outside, it should reflect in their lifestyle. From 7000 BC onwards, we have been able to observe that they are the same people. Studying Rakhigarhi has been a study of their legacy. The model Haryana household today is exactly how the households of people must have been thousands and thousands of years ago. There are too many similarities between modern day and ancient Rakhigarhi to ignore.[Harappa’s greatest centre sheds light on our today]

Reference

1. Danino, Michel. Lost River: On The Trail of the Sarasvati. Penguin Books India, 2010.