This week the world bank published data showing that China has surpassed The United States in terms of purchasing power parity. It is also interesting to note that over the past two thousand years China and India have been the worlds biggest economies for much of history, and are once again claiming those spots. Is there a specific reason for this. Has it got to do with their geo-political locations, or the climate or raw material.
http://www.economist.com/news/finance-and-economics/21623758-chinas-back
It mostly has to do with farmland. In a pre-industrial society, food is usually the limiting factor to how much population a given area supports. A combination of several factors, including large amounts of arable land, the presence of an agrarian society (which doesn't just live on arable land, but actually farms it), a climate that permits a year-long growing season, and a long history.
If you rank countries in order of arable land, the top 3 countries are:
The U.S. was not entirely an agrarian society, with some tribes practicing agriculture but many others not. Also, being part of the new world, many technological innovations made their way to it late, or not at all in the old days.
Among the countries in the old world, India and China have very large amounts of arable land in tropical and semi-tropical climates which allow several growing seasons every year. This enabled a large production of food, which in turn enabled larger economies.