Explanation:

West Bengal was formerly known as Vanga and was spread over a vast area. Ruled by several dynasties from ancient times, the actual history of this region is, however, available from the Gupta period. The prosperity and the importance of the state increased largely when the British East India Company took over the place. It was a widespread Bengal province until under the terms of the Indian Independence Act, 1947, the province of Bengal ceased to exist. The Muslim-dominated districts, namely, Chittagong, Dacca and part of Presidency and Rajshahi division went to present-day Bangladesh and the state of West Bengal came into existence in 1947. The district of Cooch Behar was merged with the state on January 1, 1950. The former Chandernogor came within the state on October 2, 1954, and the state got its present political boundary when, according to the States Reorganization Act, part of the state of Bihar was transferred to West Bengal.