Isan (Isan/Thai:ภาคอีสาน  [pʰâːk.ʔiːsǎːn]; also written as Isaan, Isarn, Issarn, Issan, Esan, or Esarn; from Pali ऐशान aiśāna or Sanskrit ऐशान aiśāna "Northeast") consists of 20 provinces in the northeastern region of Thailand. Isan is Thailand's largest region, located on the Khorat Plateau, bordered by the Mekong River (along the border with Laos) to the north and east, by Cambodia to the southeast and the Sankamphaeng Range south of Nakhon Ratchasima. To the west it is separated from northern and central Thailand by the Phetchabun Mountains.