Question

why do plains have very high population density ?

Answer 1

easy transportation
Normal atmospheric pressure
plain land
availability of rivers
easy construction
access to ground water
and main thing is
plains mostly have easy availability of food and resources

Answer 2

Much of the world is not really suitable for living or farming. Russia and Canada are too cold. Australia is too dry. A lot of the land area is deserts like the Sahara, Kalahari and Gobi or tall mountains like the Himalayas, Tibetan Plateau and the Andes. Then there are dense forests around the Equator like the Congo, Borneo and Amazon.

That leaves only a few regions with good climate, water and soil to produce sufficient food. See the red regions below? The largest of which is the northern plains of India.



Unlike other large countries, practically all of India is coloured red, with the darkest in Ganga basin - the greatest of rivers. Ganga produces the world’s largest alluvial plains and the largest delta. You can throw a seed anywhere from Punjab to Bengal and it would fall to grow to a plant thanks to the bounty of Ganga.

Now, you understand why we worship Ganga so much. It put the largest food hotspot in the world.