Question

this flat and fertile land is thickly populated called?​

Answer 1

Answer:

plains or Northern plains

Answer 2

Flat and fertile land is fit for agriculture so it is thickly populated.

EXPLANATION:

Fertile land is important for extensive farming and it is commercially viable to the farmers. Flatland is always preferable for farmers because water is accumulated and used for agriculture crops.

For example, Ganga–Yamuna daob is the best example of flat and fertile land. This region is a densely populated region in India because farmers practiced agriculture with the whole family. Transport is easily constructed in the flat land so this land is a densely populated region.