What type of cultural diffusion is the introduction of square dancing from China to Chinatown in the United States?

Migration diffusion.

Both at home and abroad, square dancing is the most positive form of cultural communication, the original lies in the fact that it is a spontaneous exchange of folk. Migration diffusion, refers to the process by which a certain cultural phenomenon is so closely linked to the person or group who owns it that when the person or group who owns it moves to a new place, it spreads the culture to that place.

Migration diffusion: the process by which a person or group under a certain culture spreads that culture to a new place when they move to that place.