As per Hindu Mythology, The Tushara Kingdom was established by the descendants of Anu, one of the son's of Yayati, the ancestor of the Yadavas (tribe of Sri krishna), the Purus - the royal lineage that included the pandavas and the Kauravas, of the epic Mahabharata.
The concept of Mleccha of Hindu Religion is simply put "Barbarians".
The IVC would have very well be barbarians to the Aryans and could have been termed Mleccha.
So, things do line up.
I have read online that the stories in the Mahabharata possibly date from the 9th century BCE at its earliest.
Gonur Tepe dates from more than 1500 years before the 9th century BCE.
Is it likely that the people who wrote the Mahabharata knew of this ancient people?
I have another question (for The_Spartan and Harsh86_Patel) : did the ones who wrote the Mahabharata and those who wrote the Vedas know of the Hittites?
If so, how did they call them?