First, it's important to be clear on what you mean by “plains.” Strictly speaking, a plain is an expanse of flat(-ish) land; it refers to topography. However, the term is sometimes used for grasslands - a biome. read more
Rivers are abundant in this region facilitating setting up of industries.So people shifted for work;as population increased; the tertiary sector boomed so more people shifted.Education and healthcare developed which accelerated the population growth.So the northern plains are the most densely populated region of India. read more
Indo Gangetic plains have high density of population due to the following reasons: Alluvial soil - The alluvial soil is very fertile and supports cultivation of different types of crops. Agriculture is the main occupation of the people in flat land with Paddy, wheat, apple, bananas and different vegetables as main crops. read more