The Constitution of India categorizes the tribes of Assam into two groups: Scheduled Tribes (Hills) and Scheduled Tribes (Plains).[1] 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.[1] Assamese language is used as the lingua franca by almost all the tribes.[1] According to the 2001 census, Scheduled Tribes made up 12.4 percent of Assam's population.[2] The Assam Tribune reported in 2009 that the tribal communities of Assam were accounted for 15.64 percent of the total population.[1]