The Shiv Sena (the name means “the army” of the 17th-century Marathi-speaking King Shivaji) was founded with a 1966 rally in Mumbai’s Shivaji Park that drew a crowd of 250,000 people. Bal Thackeray, the movement’s leader, denounced the government of the state of Maharashtra — created only six years earlier to unite Marathi speakers — for its failure to protect the interests of its constituents, who he said were losing jobs and housing to recent migrants. The Sena, which has explicitly invoked European fascist movements from the outset, describes itself in its founding documents as a “volunteer organization” rather than a political party or union; it was created to defend a Marathi claim to Maharashtra and to Mumbai. This claim was initially defended at the expense of South Indians and Communists. Later, as an ideology of Hindu nationalism became ascendant in national politics, the Marathi claim to Maharashtra and Mumbai was made at the expense of Muslim inhabitants. The Sena spread through the city’s neighborhoods, establishing shakhas (neighborhood organizations) in zopadpattis and chawls. For the Marathi-speaking people they represented, the shakhas succeeded in obtaining services from local officials that the state had never before provided: water connections, electricity, even employment. For non-Marathi speakers, the Sena was at best exclusionary; at worst, it boycotted their stores, harassed them on the street, and smashed their windows.
more from Anand Vaidya at n+1 here.