 Isan (northeastern Thailand), has 5.2 million rai of rubber trees.Most of them are concentrated in Bueng Kan Province on the Mekong River, with some 800,000 rai of rubber groves.The second and third largest rubber-growing areas in Isan are the provinces of Loei (700,000 rai) and Udon Thani (500,000 rai) of rubber farms.