who declare bengal an independent state in 1771
The Nawabs of Bengal (full title, the Nawab Nizam of Bengal and Orissa) were the rulers of the then provinces of Bengal and Orissa. Between 1717 and 1765, they served as the rulers of the subah (or province) of Bengal. However, they were only nominally subordinate to the Mughal Empire. Siraj ud-Daulah, the last independent Nawab of Bengal was betrayed in the Battle of Plassey by Mir Jafar. He lost to the British, who took over the charge of Bengal in 1757, installed Mir Jafar on the Masnad (throne) and established itself to a political power in Bengal.