Sylhet (Sylheti: ꠍꠤꠟꠐ, Bengali: সিলেট), is a metropolitan city in northeastern Bangladesh. It is the administrative seat of Sylhet Division. The city is located on the right bank of the Surma River in northeastern Bengal. It has a subtropical climate and lush highland terrain. The city has a population of more than half a million. Sylhet is one of Bangladesh's most important spiritual and cultural centres. It is one of the most important cities of Bangladesh, after Dhaka and Chittagong due to its importance to the country's economy. Sylhet produces the highest amount of tea and gas in the country. The name of Sylhet is the anglicized form of the ancient Indo-Aryan term Srihatta. In 1303, the Sultan of Lakhnauti Shamsuddin Firoz Shah conquered Sylhet by defeating Gour Govinda. Sylhet was a realm of the Bengal Sultanate. In the 16th-century, Sylhet was controlled by the Baro-Bhuyan zamindars and later became a sarkar (district) of the Mughal Empire. Sylhet emerged as the Mughals' most significant imperial outpost in the east and its importance remained as such throughout the seventeenth century. British rule began in the 18th century under the administration of the East India Company. With its ancient seafaring tradition, Sylhet became a key source of lascars in the British Empire. The Sylhet municipal board was established in 1867. Originally part of the Bengal Presidency and later Eastern Bengal and Assam; the town was part of Colonial Assam between 1874 and 1947, when following a referendum and the partition of British India, it became part of East Bengal. The Sylhet City Corporation was constituted in 2001. The Government of Bangladesh designated Sylhet a metropolitan area in 2009. The hinterland of the Sylhet valley is the largest oil and gas-producing region in Bangladesh. It is also the largest hub of tea production in Bangladesh. It is notable for its high-quality cane and agarwood. The city is served by the Osmani International Airport which is named after General M A G Osmani, the Commander of the Bangladesh Liberation Forces. People from Sylhet form a significant portion of the Bangladeshi diaspora, particularly in the United Kingdom and the United States, as well as other countries in the Middle East.