From the Yuan dynasty onward, the area was part of a central-government sponsored population movement towards the southwestern frontier, with two major waves of migrants arriving from Han-majority areas in northern and southeast China.[8] As with other parts of China's southwest, Japanese occupation in the north during World War II forced another migration of Han people into the region. These two waves of migration contributed to Yunnan being one of the most ethnically diverse provinces of China, with ethnic minorities accounting for about 34 percent of its total population.[9] Major ethnic groups include Yi, Bai, Hani, Zhuang, Dai and Miao.[10] Yunnan Province has also been identified as "the birthplace of tea...the first area where humans figured out that eating tea leaves or brewing a cup could be pleasant".[11]