Section 2(1)(f) in The M.P. Adaptation of Laws (State and Concurrent Subjects) Order, 1956
(f)"Mahakoshal region" means the territories comprised within the districts of Jabalpur, Sagar, Damoh, Mandla, Hoshangabad, Narsimhapur, Chhindwara, Seoni, Betul, Nimar, Raipur, Bilaspur, Durg, Bastar, Surguja, Raigarh and Balaghat of the State of Madhya Pradesh as existing immediately before the appointed day;