Thanh made a den in the trees and survived by foraging for fruit and vegetables and growing corn. He and his son have not had contact with anyone since.
Villagers chopping firewood raised the alarm after spotting two “jungle men” behaving oddly.
Thanh, 82, and 41-year-old Lang, who wore loincloths made out of tree bark, were found after a five-hour search. They are now having full medical check-ups.
Officials in Quang Ngai province said Thanh speaks a small amount of the minority Cor language but his son knows only odd words.
Attempts will now be made to slowly reintegrate them.