The earliest immigrant city outside China.

Chinatown, also known as China City or China City, is an area where China people live in urban areas of other countries. Chinatown was formed because early Chinese immigrated overseas and became a local minority. In the face of the new environment, they need help in the same boat, so they live in the same area together. Therefore, most Chinatown is a witness to the history of overseas Chinese.

Therefore, choose: B.