The arrival of Americans on the Great Plains complicated the Spanish-Comanche relationship. Traders and explorers like Philip Nolan probed deep into Texas and opened up commercial relations with Comanches. The Spanish expected the Comanches—whom they believed to be vassals of the crown—to banish these intruders. Instead, the Indian allies were happy for a renewal of intercourse with the Mississippi Valley. The Americans were rich, generous, and bold, and their demand for horses, buffalo products, and other prairie plunder appeared to be bottomless.
The Louisiana Purchase brought these interlopers ever closer. Before long, an American-Texas Trading Frontier emerged deep in Comancheria, much to the disgust of the Spanish. The Wichitas excelled in this American trade, and facilitated the new intrusion for a considerable share of the profits. Meanwhile, Comanche scouting parties rode south, across the Rio Grande in 1799, looking to chastise Lipans but also just looking around for targets of opportunity.
The westward push of American settlers also caused chain reactions that would push new forces on the Great Plains. Displaced tribes from east of the Mississippi migrated to Arkansas Territory, which in turn disrupted the home country of the Osages, who then sloshed over into Texas. Comanches and Osages traded raids for the next thirty years, with the Wichitas doing their part as dutiful allies until their exhaustion and collapse in 1810, their surviving people merging with the Comanches or retreating from the Red River back to the middle Brazos in a last spasm of tribal independence.