(kō'chĭn, kŏ'–), Fr. Cochinchine , historic region (c.26,500 sq mi/68,600 sq km) of Vietnam, SE Asia. The capital and chief city was Saigon (now Ho Chi Minh City ). Cochin China was bounded by Cambodia on the northwest and north, by the historic region of Annam on the northeast, by the South China Sea on the east and south, and by the Gulf of Thailand on the west. It included the rich Mekong delta, one of the world's great rice-growing regions, and, in the northeast, the southern spurs of the Annamese Cordillera, where rubber, coffee, tea, oil palm, and sugarcane plantations were established. Only the Plaine des Joncs [reed plain] and the mangrove-covered Ca Mau peninsula were not cultivated. Cochin China was originally part of the Khmer Empire . In the 17th cent. the Annamese (later called Vietnamese) gradually infiltrated through the mouths of the Mekong, increasing their commercial influence until they became masters of the region in the middle of the 18th cent. After the French…