Kullu district (Hindi: kullū, pronounced [kʊlːuː]) is a district in Himachal Pradesh, India. It borders Shimla district to the south, Mandi and Kangra districts to the west, Kinnaur to the east and the Lahaul and Spiti district to the north and east. The largest valley in this mountainous district is the Kullu Valley, which follows the course of the Beas River, and ranges in elevation from 833 metres (2,733 ft) at Aut to 3,330 metres (10,930 ft) at the Atal Tunnel South Portal, below Rohtang Pass. The town of Kullu, located on the right side of the Beas River, serves as the administrative headquarters of the Kullu district. The Kullu district also incorporates several riverine tributary valleys of the Beas, including those of the Parvati, Sainj, and Tirthan rivers, and thus some regions somewhat distant from the Kullu valley. The economy of the district relies mainly on horticulture, agriculture, tourism, and traditional handicrafts. Kullu district is part of the geographical, historical and cultural Mahasu region.