China is quite isolated because of surrounding mountains. Never seeing the other civilizations or hearing about them from nomads. It was difficult to travel there either way, one again because of the surrounding mountains, so no one was necessarily willing to venture out or into the area that was, at the time, China.
Bear in mind, I could be wrong. But I'm 98% positive that it is correct.
Answer:
C. They were located by the Atlantic coast.
