Sarlahi a part of Janakpur Zone, is one of the seventy-five districts of Nepal, a landlocked country of South Asia. The district, with Malangwa as its district headquarters, covers an area of 1,259 km² and had a population of 635,701 in 2001 and 769,729 in 2011. It is bordered to the west by the Bagmati River, to the east by Mahottari District, to the north by the Siwalik Hills, and to the south by Bihar State, India.

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