@foone Apologies for the Google link, but you might find it interesting: https://books.google.com/ngrams/graph?content=Peking%2CBeijing%2CPekin&year_start=1700&year_end=2008&corpus=15&smoothing=3&share=&direct_url=t1%3B%2CPeking%3B%2Cc0%3B.t1%3B%2CBeijing%3B%2Cc0%3B.t1%3B%2CPekin%3B%2Cc0
books.google.comGoogle Books Ngram ViewerGoogle Ngrams: Peking, Beijing, Pekin, 1700-2008