Paying tribute is accepting supremacy, to avoid further attacks, I don't know how you can call it anything else.
As for China and foreign invaders, you have to read this thread:
Nomad vs Sedentary and spread of Islam
Nomads had an edge on all sedentary societies till gun technology improved around 1500 AD, that is when nomads started loosing. But Chinese Ming dynasty beat the Mongols even before that as another poster pointed out. Mongols could not rule China more than 100 years, before they were driven out and their capital Karakorum was sacked and burned down.
It was knowledge and technology they learned from close contact with Chinese civilization that helped Mongols and even earlier Turkics spread their empire.Today the nomads that spread their empires and their successor states are closest to China than any other major sedentary societies such as Europe and India. China is also allied with Russia, another major sedentary society. China can use these alliances to beat any opposition. Japan, Vietnam or India cannot stand in the way. US is too far away to help, they are fading away as a superpower, its just a matter of few decades, what you cannot see now, will become clear in a few years:
Abe's Strategy: Rearrange Region's Power Balance | Page 19
Resistance is futile.