Hakka

According to Wikipedia, the worldwide population of the Hakka people (whom it describes as "the most diasporic among the Chinese community groups") is around 75 million.

Wikipedia describes the Hakka populations in over 20 countries, mainly in South East Asia and Australasia. The list also includes the USA and Canada, but no European countries. Elsewhere, Wikipedia lists nine Western European countries to which the Hakka people did migrate, including Great Britain. It notes that "most expatriate Hakkas in Great Britain have ties to Hong Kong as many migrated there when Hong Kong still was a British colony during a period coinciding with the Cultural Revolution of China and a minor economic depression in Hong Kong."