In the 1850s through 1890s, Comanche, Kiowa, Jicarilla Apache, Mountain Ute, and other American Indian groups lived in this part of the West, where change came with stunning speed as travel on the Santa Fe Trail grew from an occasional trickle of summer traders into heavy traffic by American teamsters, settlers, ranchers, miners, and soldiers moving west. These newcomers at times clashed with the peoples who already lived on the land. In 1851, the United States Army came to the area, and with Fort Union's firepower, food, and materiel established in this part of New Mexico, American Indians faced hard choices about war, peace, and major cultural change. Some experts estimate that more than 10,000 American Indians once lived where Fort Union's soldiers patrolled, sustaining a mobile way of life on the vast grasslands by following the buffalo herds and camping where water could be found.