Question

give reason...
why there is too much population
in india and China.....
how much.....

Answer 1

The complicated answer is very long, so I've divided it into following sections which explain population concentration on the land mass we currently identify as India:

Part 1 :  The Climate and Geography Theory and the history of world population growth

Part 2 : Factors that affect population in region and reasons behind high population of India and China

Part 3 :  The Historic Development Theory - period up to 1700s

Part 4 : The Historic Development Theory - period between 1700s to 1950s

Part 5 : The Historic Development Theory - period post 1950s

Let's first talk about the Climate and geography theory .