All the cool kids are playing with the new Google Ngram viewer, which lets you make graphs of word usage over time. You can search for usage in Chinese, but I’m not sure if they have enough Chinese books to get much out of it. Here is a search for Beijing, Peking, and Peiping.
You can see the steady decline of Peking after Nanjing becomes the capital in 1928, in part I guess because some people are using the new name of Peiping and in part because there is less reason to refer to the city when it is not the capital. (Plus, historical books might keep using Peking. This is based on date of publication. I’m not sure what they do with reprint editions.) The thing that really surprises me is that Beijing gets almost no hits for a very long time. If you fiddle with the controls almost all the early usage of Beijing comes from British English, and not much even there. Peiping dies like a dog after 1949 in British English, but the Americans keep using it for a bit. Whatever sort of English, however, the late 80’s is when Beijing and Pinyin take control.
An interesting tool, although if one tries to look at really early periods (before 1800), the data quality deteriorates because of a large number of comparatively recent books mistakenly assigned early dates.
As to the name of this particular city, it’s interesting that according to the NGram chart, “Pekin” had not quite gone out of use until the second half of the 20th century.
The Mao Zedong chart is interesting too.
Wow — I wanted to be one of the cool kids, so I tested my hypothesis that by the late 1920s in English the word “farmer” was replaced by the word “peasant.” I searched “China+peasant” vs. “China+farmer,” and in fact, the chart seems to bear this out perfectly. I have to admit that I don’t know if it’s legal to search for “China+peasant,” but I got the results I wanted so I won’t complain.
You can search for phrases.
From Vladimir’s link it looks like ‘Chinese Farmer’ got a big bump in the 30’s and in the war years, which would seem to indicate that the Nationalist were doing a good job of modernizing the international image of China. Looks like more of a bump in American English, however.