Bent's Old Fort is a fort located in Otero County in southeastern Colorado, United States. A company owned by Charles Bent and William Bent and Ceran St. Vrain built the fort in 1833 to trade with Southern Cheyenne and Arapaho Plains Indians and trappers for buffalo robes. For much of its 16-year operation as a trading post, the fort was the only major white A…Bent's Old Fort is a fort located in Otero County in southeastern Colorado, United States. A company owned by Charles Bent and William Bent and Ceran St. Vrain built the fort in 1833 to trade with Southern Cheyenne and Arapaho Plains Indians and trappers for buffalo robes. For much of its 16-year operation as a trading post, the fort was the only major white American permanent settlement on the Santa Fe Trail between Missouri and the Mexican settlements. It was initially abandoned by William Bent in 1849.