The earliest Indo-Aryan migration to Assam is estimated to have occurred between the 2nd century BCE and 1st century CE—not earlier than 500 BCE.The earliest epigraphic record suggests that the Indo-Aryan migration began latest by the middle of the 4th century CE. They came from the Gangetic Plains into a region already inhabited by people who spoke Austroasiatic and Tibeto-Burman languages.