For example, the Yuan dynasty, the Qing Dynasty, the Uighurs, and the Jurchens.
Outside of China, we see Chinese cultural practices in places like Korea, Japan and even Vietnam.
So why did all these people and states adopt Chinese culture, out of their own choice?
Well around 700 The Tang dynasty finally took Korea after many attempts under emperor Koazhong I believe, previous to that the Sui dynasty had no luck. And I know that the Tang and Song dynasties also had luck incorporating agrarian ideas and trade into Vietnam but just to attempt to explain how powerful these dynasties were, the Tang and Song had practically made Buddhism the state religion of that time if it had not been for the need for Confucius ideas to play a role in the central Bureaucracy, so that very well may be the reason for such assimilation of cultures.
Source: World Civilizations: The Global Experience Authors include: Peter N. Stearns, Michael Adas, Stuart B. Schwartz, and Marc Jason Gilbert