 AIFB(S) is mainly concentrated in Southern India, in states as Tamil Nadu and Karnataka.The party was founded in 1963 by Sasivarna Thevar, after a power vacuum led Thevar to try to take control of the All India Forward Bloc (AIFB) party in Tamil Nadu.When he failed, he quit to launch the Subhasist Forward Bloc party, a splinter group of the AIFB.