Why are there so many Americans in Beijing, China?

I originally came here to Beijing to teach ESL, but the agency screwed me over, so I have to go home next week.

I must say, though, I'm really disappointed: I thought that Bejing would have all kinds of people like Indians, Arabs, Australians, Russians and Europeans, but noooooooo. The foreigners here are almost ALL exclusively Americans. Occasionally to rarely, I hear German, French and Spanish (in that order). That's pretty much it. I have not seen one single Indian, just one Arab family, not one Australian, and not one Russian. The two main languages I hear are: Chinese. (American) English. Chinese. (American) English. Chinese. (American) English. Etc.

Let's take Hannover, Germany, for example. When I lived in Hannover, I heard not only German and Turkish, but also Arabic, Chinese, Farsi, Russian, and a multitude of African and Eastern European languages. Rarely did I ever encounter Americans/English speakers.

What makes the influx of foreigners so different? Why are Americans so attracted to Beijing? If someone were to ask, "There are Chinatowns in the U.S., so are there 'Americatowns' in China?," my answer would be, "Yes, it's called 'Beijing'!"

Though I'm sure a number of them are, they can't ALL be English teachers because they're so many of them (Americans) here. Have they simply been transferred here by their American companies, due to world economics, foreign investment, and what not?