Portugual
Between 1405 and 1433, Zheng He explored the coasts of Southeast Asia and India and the entrances to the Red Sea and the Persian Gulf.
Vietnam is a country, in the Southeast portion of Asia.
Vietnam is a country, not a continent. It is located in Southeast Asia.
No. Vietnam is in Southeast Asia.
Laos.
Singapore.
Timor Leste
Country. Located in Southeast Asia.
The only country in southeast Asia that was not fully absorbed by one or another European empires was Thailand. Japan also avoided that fate, but Japan is in east Asia, not Southeast Asia.
It's in Asia!
Thailand is itself a country. It is in the southeast of the continent of Asia.
The Philippines is a country in Southeast Asia.