Ancient India is often called the Harappan Civilization because one of the ancient cities was called Harappa. Harappa was just one of 1500 cities in the Indus River Valley. Another well-known city is called Mohenjo-Daro.Historians estimate Ancient India to be the biggest of all four early civilizations.This civilization was not discovered until the 1920’s CE, and much of this civilization remains a mystery.arappa was just one of 1500 cities in the Indus River Valley. Another well-known city is called Mohenjo-Daro. Historians estimate Ancient India to be the biggest of all four early civilizations. This civilization was not discovered until the 1920’s CE, and much of this civilization remains a mystery.