The Olmec culture of the Gulf Coast of Mexico.
The church played a very important role because it was "all around" in medieval times. On the level of almost every village there was a church and a priest which helped spread the word of the christian god. Through this, almost every person down to a villager somewhere in a village in Europe was able to come to church where people gathered on Sundays and hear new information and educate himself on various things related to faith and religion.
Uh, trading? Immigrants? WAR?
There are a lot of reasons why america should concern itself with wath China is doing, like...
The Recycling Shortage (thingy) - China put stricter guidelines for other country's waste that they deposit to China.
Immigrants - Wonder why (maybe all) major cities has a China Town? Yeah, immigrants.
More people = Economy goes up
More tourists = Cash
War - Maybe not today, but in the past, people were concerned if China was gonna start a World War.