The Indus Valley people were probably not destroyed by the so-called Aryan Invasion but they certainly knew how to build a drainage system.
The Indus Civilization is one of the oldest societies we know of, located in the greater Indus Valley of Pakistan and India, and its mature phase is dated between 2500 and 2000 BC. The Indus Valley people were probably not destroyed by the so-called Aryan Invasion but they certainly knew how to build a drainage system.