Well it states in many researches that IVC used Proto Dravidian language as their base.
Indus script - Wikipedia, the free encyclopedia
There are many striking resemblances of the Harrapan language to the Pali script that has been unearthed in Southern India in Tamilnadu.
Abugida - Wikipedia, the free encyclopedia
South indian Languages are still the only Language in the subcontinent that uses this style of writing which is charecteristic to all proto-languages except the europeans.
Ancient Scripts: Indus Script
So can you say that IVC is a Dravidian civilization to which you people have no connection to?
But there is a problem there were many races that were unearthed during excavations in IVC..those included even Mongols and the intriguing part is Ahom is also a language that is based on the proto-dravidian script. This is spoken by the Assamese and carries great resemblance to Tibetian.
Then you have the Pali script that has been one of the derivatives of the ancient Brhamni script.