Treaty of Tientsin
In 1860, Shantou, which lied in the southwest of Chenghai, was opened for foreigners and became a trading port according to Treaty of Tientsin. Shantou separated from Chenghai and became a city in 1921. Then Chenghai County was administered by Shantou conversely. On 21 June 1939, Japanese troops invaded the county town of Chenghai. Japanese force occupied Chenghai until 15 August 1945. The Communist People's Liberation Army captured Chenghai on 24 October 1949, 23 days after the People's Republic of China was founded.