David Thompson's Narrative of His Explorations in North America
I have already remarked the tribe of the Peeagans [Piikani Blackfoot] have their country along the east foot of the [Rocky] Mountains from the Saskatchewan [River] southward to the Missisourie [Missouri River], and are the frontier people and their enemies on the west side of the Mountains must break through them to make war on their allies, who thus live in security in their rear. This station has given to this Tribe something of a chivalrous character and their war parties carry on their excursions to a distance scarcely credible in search of their enemies, the Snake [Shoshoni] Indians. In the year 1787, in the early part of September[,] a party of about two hundred and fifty Warriors under the command of Kootanne Appee went off to war on the [Shoshoni]; they proceeded southward near the east foot of the Mountains and found no natives, they continued further than usual, very unwilling to return without having done something, at length the scouts came in with word that they had seen a long file of Horses and Mules led by Black Men (Spaniards) and not far off. They were soon ready and formed into one line about three feet from each other, for room to handle their Bows and Shiel[d]s, having but a few guns; the ground was a rough undulating plain, and by favor of the ground approached to near the front of the file before they were discovered, when giving the war whoop, and making a rush on the front of the file, the Spaniards all rode off leaving the loaded Horses and Mules to the war party, each of whom endevoured to make prize of a Horse or Mules. They were loaded with bags containing a great weight of white stone (Silver) which they quickly threw off the animals on[to] the ground; in doing which the saddle girths were cut, except a few, and then [they] rode off. I never could learn the number of the animals, those that came to camp at which I resided were about thirty horses and a dozen mules, with a few saddles and brindles. The Horses were about fourteen hands high[,] finely shaped, and though very tired[,] yet lively, mostly of a dark brown color, head neat and small, ears short and erect, eyes fine and clear, fine manes and tails with black hoofs. The saddles were larger than our English saddles, the side leather twice as large[,] of thick well tanned leather of a chocolate color with the figures of flowers as if done by a hot iron, the bridles had snaffle bits, heavy and coarse as if made by a blacksmith with only his hammer. The weight and coarseness of these bits had made the Indians throw most of them away.
The place this war party started from is in about 53 degrees 20 minutes N [latitude], [probably just south of Edmonton, Alberta] and the place where they encountered the Spaniards conveying the silver from the mines is about the latitude of 32 degrees north, a distance of 1500 miles in a direct line.
[At this time, the Spanish mined silver near El Paso, Texas, and in the present day Mexican State of Chihuahau, under Juan Bautista de Anza.]