After the Franco-Thai War, Thailand inherited parts of French Indochina and its railway in the east. At that point, the railway from Phnom Penh and Aranyapratet has not yet been fully constructed, with the section between Mongkol Borey and Aranyapratet still unfinished. In October 1941, the construction of the remaining section began, and on 8 December, Japanese troops invaded Thailand, took over the construction and finished the missing link in about two weeks. Trains started running between Phnom Penh and Bangkok on 22 December.