Before Texas was claimed in the 18th century as a part of the Viceroyalty of New Spain by the Spanish Empire, the Dallas area was inhabited by the Caddo people. Later, France also claimed the area, but in 1819 the Adams-Onís Treaty made the Red River the northern boundary of New Spain, officially placing the future location of Dallas well within Spanish territory. The area remained under Spanish rule until 1821, when Mexico declared independence from Spain and the area became part of the Mexican state of Coahuila y Tejas. In 1836, the Republic of Texas broke off from Mexico to become an independent nation. In 1839, Warren Angus Ferris surveyed the area around present-day Dallas. Two and a half years later, John Neely Bryan established a permanent settlement near a river he found and called that settlement Dallas. The Republic of Texas was then annexed by the United States in 1845 and Dallas County was established the following year. Dallas was formally incorporated as a city in February 1856. The name of the city has uncertain origins. See History of Dallas, Texas (1839-1855) for more information on that.