The Nawab of Bengal who made overall revenues of Bengal in lieu of an annual pension of Rs. 50 lakh was Najim-ud-daula.

The Nawab of Bengal, Najim-ud-daula, played a significant role in the administration and revenue collection of Bengal during the 18th century. He was appointed as the Nawab by the Mughal Emperor Aurangzeb in 1717.

Background:
During the Mughal rule, the administration of Bengal was decentralized, and the Nawabs were appointed to manage the region on behalf of the Mughal Empire. The Nawabs had the responsibility of maintaining law and order, collecting revenue, and managing the affairs of the region.

Najim-ud-daula's Reforms:
Najim-ud-daula implemented several reforms to improve the revenue collection system in Bengal. He introduced a system called the "Dastak," which was a pass that allowed merchants to transport goods without paying taxes. This system aimed to encourage trade and commerce in the region and boost revenue collection.

Additionally, Najim-ud-daula reformed the land revenue system. He introduced a new method known as the "zabti" system, which involved fixing the revenue demand for each plot of land based on its productivity. This system helped in streamlining the revenue collection process and ensured a fair assessment of taxes from the peasants.

Revenue Collection and Pension:
Under Najim-ud-daula's administration, the revenue collection in Bengal increased significantly. The Nawab managed to accumulate vast wealth through his reforms and efficient administration. As a result, he negotiated an agreement with the Mughal Emperor to receive an annual pension of Rs. 50 lakh in exchange for transferring the overall revenue of Bengal to the imperial treasury.

This agreement allowed Najim-ud-daula to retain a significant portion of the revenue collected in Bengal while providing a substantial pension to the Mughal Empire. It further consolidated his power and influence in the region.

Legacy:
Najim-ud-daula's tenure as the Nawab of Bengal marked a period of stability and prosperity in the region. His reforms in revenue collection and administration played a crucial role in strengthening the economy of Bengal. However, his accumulation of wealth and the transfer of revenue to the Mughal Empire contributed to the growing discontent among the British East India Company, eventually leading to the Battle of Plassey in 1757.

In conclusion, Najim-ud-daula, as the Nawab of Bengal, implemented significant reforms in revenue collection and administration. His successful management of Bengal's revenue allowed him to negotiate an agreement with the Mughal Emperor, receiving an annual pension of Rs. 50 lakh in exchange for transferring the overall revenue of Bengal to the imperial treasury.