Who did john hay negotiate with to establish the open door policy

It would be "China" that John Hay negotiated with to establish the open door policy, since trading with China greatly benefitted the United States (and China as well to some extent). 

high entry costs prevent new producers from entering the market.

explanation:

an oligopoly is a term used to clarify the structure of a particular market, industry, or organization. a market is considered oligopolistic or amazingly focused when it is shared between a few companies.

They were constantly being overlooked as a people and were being controlled by people who weren't really native to their homeland.