is the second largest district of Uttar Pradesh, India. Sonbhadra is the only district in India which borders four states namely Madhya Pradesh in west, Chhattishgarh in south, Jharkhand in south east and Bihar in the east. The district has an area of 6788 km² and a population of 1,862,559, with a population density of 270 persons per km².It lies in the extreme southeast of the state, and is bounded by Mirzapur District to the northwest, Chandauli District to the north, Kaimur and Rohtas districts of Bihar state to the northeast, Garhwa district of Jharkhand state to the east, Balrampur District of Chhattisgarh state to the south, and Singrauli district of Madhya Pradesh state to the west.
The district headquarters is in the town of Robertsganj. Sonbhadra
district is an industrial zone and it has lots of minerals like bauxite, limestone, coal, gold etc.
Sonbhadra is called as "Energy Capital of India" because there are so many power plants.
Sonbhadra lies between vindhya and Kaimur hills, and its topology and natural environment prompted First Prime minister of India Pt. Jawarharlal Nehru to refer to Sonbhadra as The Switzerland of India.