Question

why are northern plain rich and fertile

Answer 1

Northern plain is comprised of some vital rivers, namely the Indus and its five tributaries, the Ganges, the Yamuna and the Brahmaputra in the Northeast.

All these rivers carry loads of alluvium while flowing down from the mountains, which are deposited over the lands on the banks of these rivers and their tributaries.

Thus, the entire northern plain is highly rich and fertile, where staple crops like rice and wheat are grown in abundance.