On the India facing side of the Southeast Asia, China never held much influence due to the mountains, jungles and the distance. However, on the China facing side of the Southeast Asia, it is very time dependent with the exception of Vietnam.

In China facing side of Southeast Asia, with exception of Vietnam, influence waxed and waned depending on the strength of the dynasty and distance from China. Majority of nations in China facing side of Southeast Asia were tributary of China, but they remained so for trade reasons and as such, traders were the main source of influence. Kingdoms in modern day areas Cambodia, Thailand and southern Indonesia were under less influence while areas of modern day Phillippines, Malaysia and northern Indonesia were impacted more cyclically. When a dynasty in China is strong, there is strong trade presence and adoption of Chinese influences. There are records of adoption of Chinese style clothing, art, religion, shipbuilding and technology at the height of each dynasties. The most prononunced are Han, Song and Ming due to their focus on trade. However, as dynasties wane, there is equally marked tapering of Chinese influence in favour of Indo-Arabic influence which remains relatively stable until European colonization.

In Vietnam there was more direct influence due to the geography of being connected to China. In parts of its history, the northern parts were occupied by differing dynasties and they were considered one of principal tributaries. You can easily see growing sinification of the area especially in mid-Han dynasty as Chinese writing system is adopted and Confucian scholars are employed as government beaurocrats. From Han dynasty on, Vietnam remain under Sinosphere unlike other nations in the region which fall under largely Indo-Arabic influences as visible in writing system or spread of Islam. The Chinese influences remains in the region until replaced by the French during French colonization of the area.