The correct answer is C) The country was sparsely populated and had no system of defense.
China was so easily overtaken by European imperialists in that The country was sparsely populated and had no system of defense.
Indeed, in those years, China lacked a formal and well-trained army.
Those elements facilitated invaders to enter Chinese territory although the geography of the country did not help at all. The mountains and peaks of the South were a natural barrier that isolated China during many years. The Mongols invaded China and ruled in big portions of the country in the 1120's AD. Another example of a foreign country invading China was the Japanese occupation from 1937 to 1945.
