Answer:
First, they certainly did have some foreign influence. Buddhism was very influential, especially between the second and seventh centuries, and it came from India. They also took some ideas from the nomads of Central Asia and from Southeast Asia
Explanation:
But, with the major exception of Buddhism, they really did develop with little influence. The reason can be seen easily if you look at a relief map and have some idea where the other centers of civilization were. On China's southwest are the tallest mountains in the world: the Himalayas and the Kunlun mountain chains. To China's northeast, just north of the Kunluns is the Taklamakan desert, widely considered the most desolate place on Earth outside of Antarctica. People traveled along the edges of the Taklamakan, where they could find water, but it was difficult and dangerous.
These natural features made a wall between China and the civilizations in India and the Middle East that was very difficult to cross. People still did, along the ancient Silk Road and in boats around southeast Asia, but not in large numbers, and mostly after the central features of Chinese civilization had already developed
