Actually, the People's Republic of China officially lists 56 ethnic groups, one of which is the majority Han Chinese, the same group carrying the 'Chinese' tag as found in Taiwan, Indonesia, Thailand, Malaysia, Singapore, USA, Canada and all over the world where there is a Chinese community or a Chinatown.
Also due to political reasons, the PRC includes the Ethnic Minorities in Taiwan which PRC terms as 'Gaoshan' people. They are the indigenous people found only in Taiwan and not found on mainland China.
Some of the ethnic groups form the majority population in countries neighbouring PRC: Mongol (Mongolia), Korean (North & South Korea), Kazak (Kazakhstan), Kirgiz (Kyrgyzstan), Tajik (Tajikistan), Jing (Vietnam), Russian (Russia) and Ozbek (Uzbekistan).
For more info, visit http://en.wikipedia.org/wiki/List_of_ethnic_groups_in_China
Photos below arranged top to bottom according to decreasing population size.
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