one cause of tensions between mexico and the united states in the years leading up to the mexican–american war (of 1846-1848) was the frequent raiding of cattle by native americans from north of the border. mexico's military and diplomatic capabilities had declined after it attained independence which left the northern half of the country vulnerable to the apache, comanche, and navajo. these tribes, especially the comanche, took advantage of mexico's weakness by undertaking large-scale raids hundreds of miles deep into the country to steal livestock for their own use and to supply an expanding market in texas and the united states. these raids left thousands of people dead and devastated northern mexico. when american troops entered northern mexico in 1846 they found a demoralized people and little resistance from the civilian population.