This video, featuring a speaker I've never heard of, is very interesting. It's the third part of a series.
So, that led me to do a quick search about blacks in Vietnam, and sure enough, some here is research by Runoko Rashidi: the black Vietnamese were known as the Champa, original conquerors of the region. They defeated the Chinese, who referred to them as k'un-lun (a phrase I've come across a few times online) and found their way to the Philippines later, theorizes H. Otley Beyer.
More of Rashidi's work reveals his conviction that the Agta of the Philippines — known more commonly as Negritos and Aeta — are descendants of those early seafarers from Africa by way of South India. (Note that the same South India/Andaman Islands connection is also theorized to be the connection point for the Ainu of Japan, according to DNA comparisons.)
"They were the aborigines of the Philippines, and for a long time had been master of Luzon. At a time not very far distant, when the Spaniards conquered the country, the Aetas levied a kind of blackmail from the Tagalog villages situated on the banks of the lake of Bay (Laguna de Bay). At a fixed period they quitted their forests, entered the village, and forced the inhabitants to give them a certain quantity of rice and maize....After the conquest of the Philippines by the Spaniards, the latter took upon themselves the defense of the Tagalogs, and the Aetas, terrified by their firearms, remained in the forests, and did not reappear among the Indians."
—Dr. Pedro A. Gagelonia, a Filipino scholar
Here's an interesting quote from the foreign minister of Papua New Guinea back in 1976:
"Africa is our motherland. All of the Black populations which settled in Asia over the hundreds of thousands of years, came undoubtedly from the African continent. In fact, the entire world was populated from Africa. Hence, we the Blacks in Asia and the Pacific today descend from proto-African peoples. We were linked to Africa in the past. We are linked to Africa in the present. We will be linked to Africa in the future."