Also known as the Indus Valley Civilization—covered about 300,000 square miles. Had some kind of writing which has not been deciphered. Language unknown but maybe related to the later Dravidian languages—certainly not Indo-European.
Robinson mentions "a substantial inscription found at Dholavira near the coast of Kutch in 1990, which appears to have been a kind of sign board for the city." [p 295]Lost Languages: The Enigma Of The World's Undeciphered Scripts
by Andrew Robinson
Here's how our decendants will be able to read and speak! American English:
Note: the pyramid on page one is only as tall as a man, but there are hundreds to thousands scattered across America. A 5,000 year great-g-g-g-g-g-g-g-grandson need only find one to kick start a early-to-mid 1900s level of civilization.
Each pyramid has the microtext equivalent of about 30,000 print books and enclosed microscopes so that the text is in a human readable form of everything from smelting metals, to the horse collar and plow, to soap and sanitation, to art and culture, to the scientific method, to having a representative democracy and more!
It would be like Colonial America getting a time capsule from Atlantis!