The South Thailand Insurgency is an ethnic separatist insurgency taking place in Southern Thailand, predominantly in the Malay Pattani region, made up of the four southernmost provinces of Thailand. In Thailand it is known simply as Unrest in southern Thailand (Thai: ความไม่สงบในชายแดนภาคใต้ของประเทศไทย). The former Sultanate of Patani was conquered by the Thais in 1785 and has been governed by them ever since. Thai ownership was confirmed by the Anglo-Siamese Treaty of 1909. Although low level separatist violence has occurred in the region for decades, the campaign escalated in 2004, occasionally spilling over into other provinces.[5]