The Bihar Subah (Persian: صوبه بهار) was a province (suba) of the Mughal Empire that was formed in 1575. It was one of the original twelve subas established by Emperor Akbar. Its seat was in the city of Patna which was also known as Azimabad. The seat of Azimabad was named after the Mughal prince, Azim-ush-Shan who was the son of Emperor Shah Alam I.
The suba was bordered to the west by the subas of Illahabad and Awadh and to the east by Bengal Subah.
The Bengal Subah (Bengali: সুবাহ বাংলা, Persian: صوبه بنگاله), also referred to as Mughal Bengal and Bengal State (after 1717), was the largest subdivision of the Mughal Empire encompassing much of the Bengal region, which includes modern-day Bangladesh, the Indian state of West Bengal, and some parts of the present-day Indian states of Bihar (from 1733), Jharkhand and Odisha between the 16th and 18th centuries. The province was established following the dissolution of the Bengal Sultanate, a major trading nation in the world, when the region was absorbed into the Mughal Empire. Bengal was the wealthiest region in the Indian subcontinent.
Aurangzeb (r. 1658–1707) described Bengal Subah as 'the paradise of Nations' and the "Golden Age of Bengal". It alone accounted for 40% of Dutch imports from Asia. The eastern part of Bengal was globally prominent in industries such as textile manufacturing and shipbuilding, and it was a major exporter of silk and cotton textiles, steel, saltpeter, and agricultural and industrial produce in the world. The region was also the basis of the Anglo-Bengal War.
The Darbhanga Raj, also known as Raj Darbhanga and the Khandwala dynasty, was a chieftaincy located within the Mughal province of Bihar which controlled territories, not all contiguous, that were part of the Mithila region now divided between India and Nepal. The rulers of Raj Darbhanga were Maithil Brahmins and their seat in the town of Darbhanga became the core of the Mithila region as the rulers were patrons of Maithil culture and the Maithili language.
At its peak, the dynasty encompassed over 4000 square miles (10,360 km) and is described as the "largest and richest of the North Bihar zamindaris and one of the greatest zamindaris of British India". Despite not being recognised as a princely state by the British Raj, Darbhanga was larger and held more magisterial powers than many princely states, particularly those in Western India.