The eastern black crested gibbon (Nomascus nasutus), also known as the Cao-vit black crested gibbon or the Cao-vit crested gibbon, is a species of gibbon from southeast China and north Vietnam. From the 1960s until the 2000s there had been no confirmed sightings of the eastern black crested gibbon and it was thought to be possibly extinct. In 2002 a small population was rediscovered in the Trùng Khánh District, Cao Bằng Province, in northeast Vietnam. In 2005 it was estimated that this population included about 35-37 individuals, and about 10 remain just across border in Jingxi County, Guangxi, China. It was thought to be extinct in China before the species was re-discovered by members of Kadoorie Conservation China.