San Augustine County is in the pine belt of East Texas and is bounded by Shelby County on the north, Sabine County on the east, and Nacogdoches and Angelina Counties on the west and south. Inhabited for centuries by the Ais tribe of the Hasinai Indians (part of the Caddo Confederacy) at the time of European contact, what would become San Augustine County remained sparsely settled by colonists through the first half of the 18th century. Most notably there was the Mission Nuestra Senora de los Dolores de los Ais, built by Father Antonio de Jesus Margil in 1716. The purpose of the mission was to convert Indians and establish a Spanish influence in an area contested with the French. The mission lasted only 3 years, but the Spanish came back shortly thereafter and remained a presence in San Augustine, with the exception of a brief period in the 1770s, until the Mexican Revolution. The county was part of what was known as the "Neutral Ground" (the disputed, and therefore undefined border between Spanish/Mexican Texas and American Louisiana) and home to many squatters settling without land grants in the late 1700s and early 1800s. It was not until 1827 that Mexico organized San Augustine into the District of Ayish Bayou. In 1834, authorities changed the District to the Municipality of San Augustine, which included present San Augustine, Sabine and Shelby counties as well as parts of Panola, Newton, and Jasper counties. Several years later (1837), the new Republic of Texas created San Augustine County, with the county seat at San Augustine.