Free trade helps to build the roads and infrastructure needed. The cost of building roads needs to be paid for, if it isn't worth transporting things from point A to point B the road is pointless. As the cost of trade goes down it self-reinforces by making people willing to contribute to better infrastructure. Of course when the road doesn't exist at all sometimes the investment to make the road is too high for people to realize that it is worth it.

China contributing is potentially a good thing (or potentially bad for reasons others have debated). This trade zone doesn't need their contribution to be successful, but it helps.