When the United States purchased Louisiana from France in 1803, American authorities insisted the agreement also included Texas. The boundary between New Spain and the United States was finally set at the Sabine River in 1819, at what is now the border between Texas and Louisiana. Eager for new land, many United States settlers refused to recognize the agreement. Several filibusters raised armies to invade the area west of the Sabine River. In 1821, the Mexican War of Independence included the Texas territory, which became part of Mexico. Due to its low population, the territory was assigned to other states and territories of Mexico; the core territory was part of the state of Coahuila y Tejas, but other parts of today's Texas were part of Tamaulipas, Chihuahua, or the Mexican Territory of Santa Fe de Nuevo México.