Before they started on their retreat, however, some of the strongest of the party followed the trail of the animal that had saved their lives to the river, where, filling all the canteens with pure water, they returned to their comrades, who were, after drinking, able to march slowly toward the Arkansas. Following that stream, they at last arrived at Taos, having experienced no further trouble, but missed the trail to Santa Fe, and had their journey greatly prolonged by the foolish endeavour of the leader to make a short cut thither. As early as 1815, Auguste P. Chouteau and his partner, with a large number of trappers and hunters, went out to the valley of the Upper Arkansas for the purpose of trading with Indians, and trapping on the numerous streams of the contiguous region. The island on which Chouteau established his trading-post, and which bears his name even to this day, is in the Arkansas River on the boundary line of the United States and Mexico. It was a beautiful spot, with a rich carpet of grass and delightful groves, and on the American side was a heavily timbered bottom. While occupying the island, Chouteau and his old hunters and trappers were attacked by about three hundred Pawnees, whom they repulsed with the loss of thirty killed and wounded. These Indians afterward declared that it was the most fatal affair in which they were ever engaged. It was their first acquaintance with American guns. The general character of the early trade with New Mexico was founded on the system of the caravan. She depended upon the remote ports of old Mexico, whence was transported, on the backs of the patient burro and mule, all that was required by the primitive tastes of the primitive people; a very tedious and slow process, as may be inferred, and the limited traffic westwardly across the great plains was confined to this fashion. At the date of the legitimate and substantial commerce with New Mexico, in 1824, wheeled vehicles were introduced, and traffic assumed an importance it could never have otherwise attained, and which now, under the vast system of railroads, has increased to dimensions little dreamed of by its originators nearly three-quarters of a century ago.