According to the 2001 census, the Scheduled Tribes population as in percentage of the total population of Assam was 12.4 percent.The Assam Tribune reported in 2009 that the tribal communities of Assam now officially account for 15.64 percent of the total population.[2] The Constitution of India categorizes the tribes of Assam into two groups: Scheduled Tribes (Hills) and Scheduled Tribes (Plains). Since hills tribes living in the plains and plains tribes living in the hills in large numbers are not recognised as scheduled tribes in the respective places, the census data may not reflect the correct figures.The Assam Tribune has claimed that if these categories of tribes are counted the actual population. Assamese language is used as the lingua franca by almost all the tribes.[2]Various other indigenous communities of Assam were all tribes but were later converted into caste through Sanskritisation or proselytization like the Ahoms, Morans, Motak, Keot(Kaibarta), Sutiya, Koch Rajbongshi etc.