Here's why we believe this:
* Linguistic connections: There are significant linguistic connections between Sanskrit and the Indus Valley language. While the script itself remains undeciphered, scholars have identified words and grammatical structures similar to Sanskrit in the Indus Valley script.
* Geographical proximity: The Indus Valley Civilization was located in the Indian subcontinent, where Sanskrit originated.
* Evidence from later texts: Some Vedic texts mention a language and script that resemble the Indus Valley script, suggesting a connection.
However, it's important to note that the precise relationship between the Indus Valley language and Sanskrit is still debated among scholars. While there is evidence suggesting a link, it's not definitively proven that Sanskrit was the spoken language of the Indus Valley Civilization.
Therefore, while we can't say with absolute certainty that the Indus Valley Civilization used Sanskrit, it is a strong possibility based on available evidence.