the route skirted the northern edge and crossed the northwestern corner of comancheria, the territory of the comanches. they demanded payment for allowing people to use the trail. comanche raiding farther south in mexico isolated new mexico. this made the area more dependent on the american trade. it also gave the comanches a steady supply of horses. by the 1840s trail traffic along the arkansas river valley was so heavy that bison herds could not reach important seasonal grazing land. this contributed to their decline which in turn hastened the decline of comanche power in the region. the trail was used as the 1846 u.s. invasion route of new mexico during the mexican–american war.