Northeast Thailand or Isan (Isan/อีสาน, ʔīː.sǎːn; ; also written as Isaan, Isarn, Issarn, Issan, Esan, or Esarn; from Pāli isāna or Sanskrit ईशान्य īśānya "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 Laos–Thailand border) 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. Isan covers making it about half the size of Germany and roughly the size of England and Wales. The total forest area is or 15 percent of Isan's area. Since the beginning of the 20th century, northeastern Thailand has been generally known as Isan, while in official contexts the term phak tawan-ok-chiang-nuea (ภาคตะวันออกเฉียงเหนือ; 'northeastern region') may be used. The majority population of the Isan region is ethnically Lao, but distinguish themselves not only from the Lao of Laos but also from the Central Thai by calling themselves khon Isan or Thai Isan in general. However, some refer to themselves as simply Lao, and academics have recently been referring to them as Lao Isan or as Thai Lao, with the main issue with self-identification as Lao being stigma associated with the Lao identity within Thai society. The Lao Isan people are aware of their Lao ethnic origin, but Isan has been incorporated as a territory into the modern Thai state through over one hundred years of administrative and bureaucratic reforms, educational policy, and government media. Despite this, since the election of Thaksin Shinawatra as prime minister in the 2001 Thai general election, the Lao Isan identity has reemerged, and the Lao Isan are now the main ethnolinguistic group involved in the pro-Thaksin "Red Shirt movement" of the United Front for Democracy Against Dictatorship. Several Thai prime ministers have come from the region.