Northern plains lie in the south of Himalayas Mountains and north of Deccan plateau. It is formed by flooding of three major rivers- Indus, Ganga and Brahmaputra. It is drained by many other rivers like Yamuna, Ghaghara, Gandak etc. These are perennial rivers which flow throughout the year which helps plains maintain their fertility. It has the largest tract of 2400 km of alluvial soil in the world. The soil of these plains is very fertile. A large number of people live here who are dependent on agriculture for livelihood.