In 1904 the territory of Cambodia was increased by the addition to it of the Siamese provinces of Melupre and Bassac, and the maritime district of Krat, the latter of which, together with the province of Dansai, was in 1907 exchanged for the provinces of Battambang, Siem-reap and Sisophon.
This 25 kilometre neutral zone was abolished in 1905 when France surrendered Chantabun to the Siamese, who in their turn ceded the port of Krat and the provinces of Melupre and Bassac, together with various trading concessions to France on the right bank of the Mekong.
The Dom Pia Fai throws up a point over 4000 ft., and the south-eastern range which divides the narrow, littoral, Chantabun and Krat districts from Cambodia, has the Chemao, Saidao and Kmoch heights, between 3000 and 5000 ft.
To the east, in the Bang Pakong river-basin and down the eastern shore of the gulf, are Pachim, a divisional headquarters; Petriou; Bang Plasoi, a fishing centre, with Rayong, Chantabun (q.v.) and Krat, producing gems and pepper.
In 1907 a further convention was made with France, Siam returning to the French protectorate of Cambodia the province of Battambang conquered in 181r, and in compensation receiving hack from France the maritime province of Krat and the district of Dansai, which had been ceded in 1904.