The American frontier moved steadily westward from the 1630s to the 1880s (with occasional movements north into Maine and Vermont, and east from California into Nevada). The "West" was always the area beyond that boundary.Most often, however, the "American West," is used for the area west of the Mississippi River during the 19th century.
Anglo Texans greeted the end of the U.S-Mexican War in 1848 with the hope that federal troops would at last put an end to violent encounters with Indians and Mexicans along the state's western and southern borders and open the vast frontier to settlement. All too quickly the lure of nearly free and unbroken land attracted a multitude of pioneers. So rapidly, in fact, that it thrust some white settlers far beyond the protection of the eight new military installations established at war's end, running from Fort Worth in North Texas to Fort Duncan on the Rio Grande.
In response, the U.S. Army in 1851 began establishing a new line of forts a hundred miles beyond the original vanguard. Others were located in the Big Bend country along the Rio Grande and in extreme South Texas.The Great Raid of 1840 was the largest raid ever mounted by Native Americans on white cities in what is now the United States.It followed the Council House Fight, in which Republic of Texas officials attempted to capture and take prisoner 33 Comanche chiefs who had come to negotiate a peace treaty, killing them together with two dozen of their family and followers. The Texas Officials were determined to force the Comanche to release all white captives among them. To avenge what the Comanche viewed as a bitter betrayal by the Texans, the Comanche war chief Buffalo Hump raised a huge war party of many of the bands of the Comanche, and raided deep into white-settled areas of Southeast Texas.