Bihar is a state in East India. It is bounded by Uttar Pradesh to the west, Nepal to the north, West Bengal to the east and Jharkhand to the west. Bihar has notified forest area of 6,764.14 km², which is 7.1% of its geographical area. The sub-Himalayan foothills of the Someshwar and Dun mountain ranges in West Champaran district clad in a belt of moist deciduous forest. As well as trees, this consists of scrub, grass and reeds. Here the annual rainfall is above 1,600 mm and this promotes luxuriant sal forest (Shorea robusta) in the favoured areas. Bihar has 3,208 km² (~3.41%) of Protected Area and 76.30km² of Protected non-Forest Area.
Bihar is mainly a vast stretch of very fertile flat land. It is drained by the Ganges River, including northern tributaries of other rivers. The Bihar plain is divided into two unequal halves by the river Ganges which flows through the middle from west to east. Other Ganges tributaries are the Son, Budhi Gandak, Chandan, Orhani, and Phalgu. The Himalayas begin at foothills, a short distance inside Nepal but influence Bihar's landforms, climate, hydrology, and culture. The Central part of Bihar has some hills, for example, the Rajgir Hills. The Himalayan Mountains are to the north of Bihar, Nepal. To the south is the Chota Nagpur plateau, which was part of Bihar until 2000 but is part of the separate state called Jharkhand.