Mandarin is one of five major regional languages of China. It spreads wider than any other regional variety, from the whole northern part of China to Yunnan Province in the southwest corner of China. In that big area there are many regional differences in vocabulary, so somebody who moves from Beijing to Yunnan could not understand people there who were speaking their own dialect, Yunnanhua. The problem is bigger than for a person in Great Britain or the United States to go to Australia. Therefore, starting in the 1920s, the Chinese government set up a national language based on the Beijing dialect and on the most widely understood words and pronunciations.