China appears to be a place where multiple advancements in technology were independently discovered. Plant domestication by 7500 BC, writing by 1300 BC. These all appear to be consistently behind the Fertile Crescent, but only by about 1000 years.
The expansion of farming was stunted from north to south, but rivers allowed them to spread east to west, from the coast inland. In Europe the main axis was east-west also, allowing the easy spread of crops across Europe.
China seems to have been relatively united for the past several thousand years.
It appears that China did have large effects on other parts of Asia and Polynesia. Many languages from South China expanded into southeast Asia in the first few 1000 years BC.
The unity of China may have been its undoing. Since it was unified under one centralized government, it lost the selective pressure that was felt in Europe.
Japan, for example, originally had some of the best guns and weaponry in the entire world; however, they eventually eliminated guns because they believed that it detracted from the honor of battle. They were able to go backwards in technology because there were no other countries to take it over. If a European country had moved backwards like this, they would immediately be taken over by another country that had moved forward. If Japan itself was not unified, then there would have been competition between those separate states that would have prevented the elimination of technology.
Since these Asian countries were so unified, they had very minimal competition between states. This allowed them to become very conservative, just in time for other countries to show up.
There are other examples of isolationism causing backwards advances in technology. The natives of Tasmania required relatively advanced ships (for their time) to travel to an island that is completely out of sight from the mainland of Eurasia. Once on the island, the devanced in technology all the way back to stone tools (not even bone), and stayed that way until modern times.