 In 1956, the Manbhum district was partitioned between Bihar and West Bengal under the States Reorganization Act and the Bihar and West Bengal (Transfer of Territories) Act 1956.106 districts spanning 10 states across India, described as being part of the Left Wing Extremism activities, constitutes the Red corridor.In West Bengal the districts of the Paschim Medinipur, Bankura, Purulia and Birbhum are part of the Red corridor.