The Narmada is the longest river in Madhya Pradesh. It flows westward through a rift valley, with the Vindhya ranges sprawling along its northern bank and the Satpura range of mountains along the southern. Its tributaries include the Banjar, the Tawa, the Machna, the Shakkar, the Denwa and the Sonbhadra rivers. The Tapti River runs parallel to Narmada, and also flows through a rift valley. The Narmada–Tapti systems carry an enormous volume of water and provide drainage for almost a quarter of the land area of Madhya Pradesh. The Narmada river is considered very sacred and is worshipped throughout the region. It is the main source of water and acts as a lifeline to the state.