The rich Indus plains in the upper part include the areas of Punjab (both India and Pakistan). The five tributaries of the river Indus in this region have created a vast alluvial plain earning the name ‘bread-basket’ of the subcontinent. In the east these plains merge with the Gangetic delta. The lower Indus valley and the delta constitute Sind. This covers the areas between the Baluchistan hills on the north–west and the Thar desert on the south-east. This region is also gifted with rich alluvial soil suitable for the cultivation of rice and wheat.
The Gangetic plains of northern India were formed by the deposition of alluvium in the trough facing the Himalayas, and the erosion caused by the rivers. They can be subdivided into three – (i) Upper, (ii) Middle, and (iii) Lower. The Upper plains largely include the doab in western and central Uttar Pradesh. The Middle Gangetic plains correspond to eastern Uttar Pradesh and Bihar. This starts from Allahabad, the confluence of the Ganges and Yamuna and the terminal point of doab. The lower plains include the areas of Bengal. These are formed by the alluvial deposition of the rivers Ganga and Brahmaputra. The Eastern Indian region constitutes the coastal plain of Orissa. This is located to the south-west of the Gangetic delta and the eastern end of the hills of Central India. Mahanadi is the major river which along with other rivers has drained this region since ancient period. Western India is located on the western end of the Central Indian belt. This corresponds to the modern state of Gujarat. The central peninsula of this region is called Kathiawar or Saurashtra peninsula. The northern Gujarat is a semi-arid region whereas the southern areas on the western coast are fertile. Rann of Kutch is the low-lying area which turns into a swamp during the monsoons. The Saurashtra region is close to the Indus and has often served as a transition zone between Sind and lands farther west. The rivers Narmada, Tapti, Sabarmati and Mahi have helped in the formation of the coastal plains by carrying and depositing alluvium brought from the Central Indian hills. The Central Indian belt constitutes the areas falling under southern Bihar, Chhattisgarh, western Orissa and eastern Madhya Pradesh. It is a hilly region where the elevation of hills is not very high. But these hills are broken by steep slopes and intersected by valleys. Except the Aravallis, all other hills run from east to west.