Why is Chinatown called 唐人街 in Chinese?

唐人街 is one of the different ways the Chinese refers to Chinatowns in the US and other countries. (the others being 華埠 or 中國城 [direct translation of Chinatown])

唐 refers the Tang Dynasty in China, and it's one of the most important times in Chinese history that the Chinese may associate themselves as "people of the Tang Dynasty" as 唐人.