How did corn cultivation develop large civilizations in central and south america?

i believe that the answer to the question provided above is that  establishing smaller ethnic communities within larger communities  gives more chance for people to know each other more but this might lead to the  conflict between groups.

codfish influenced the yankee trade because they traded it with the americans and the americans traded livestock, molasses and stuff that they can make clothes out of (like wool, and leather). they also could make weapons to.