Interesting. Btw, South East Asia is not related to China. The early settlers (about 20,000 years - 200,000 years) established the Malayan Archipelago, and the migration of people from here was to the US, so you might see more similar features between the Native Americans and the South East Asians.
But over time, heavy colonisation and high trade activities in the last 700 years established communities of various races as well as mix races and cross cultures (Portuguese, Dutch, British, Spain, Japan, Chinese, Indian, Persian).
More recent times (about 70 years post independence from the British) established separation based on socially constructed race, political ideology and religion. British also brought in the caste influence so in some countries, economic accessibility based on races still exist.
But all in all, South East Asia (Malaysia, Singapore, Indonesia, Thailand, Vietnam) is not the same as South Asia (India, Pakistan, Sri Lanka, Bangladesh) and Asia Pacific (China, Japan, Korea, Taiwan, Mongolia)