This [smallpox epidemics in the first half of the 19th century], and probably the increased aggressiveness of other Plains tribes with the spread of firearms as well, led to a recession of the Shoshone and their retreat to the west in the middle of the nineteenth century. A final wave of expansion onto the Plains came with white aid, following the treaty at Fort Bridger, July 3, 1868.

While agreeing in part with these conclusions, we would not confine the Shoshone restriction to the territory west of the Continental Divide to such limited periods. The following data suggest, rather, that "the heart of this people's territory," as Shimkin describes the Wind River country, did not extend west of the Wind River Range from at least 1800 until the reservation period and that the Shoshone, while frequently entering the Missouri River drainage, did so only for brief periods and usually in considerable fear of attack.

In Washington Irving's account of the Astoria party, one of our earliest reliable sources on the Wyoming Shoshone, the author tells how the Shoshone were pushed out of the Missouri River buffalo country after the North West and Hudson's Bay Companies put firearms in the hands of the Blackfoot (Irving, 1890, p. 197):

Thus by degrees the Snakes have become a scattered, broken-spirited, impoverished people, keeping about lonely rivers and mountain streams, and subsisting chiefly upon fish. Such of them as still possess horses and occasionally figure as hunters are called Shoshonies.

The westward-bound Astoria party traveled up the Wind River Valley in the middle of September, 1811, without sighting any Indians (ibid., pp. 199-200). This was exactly the time of year when, according to contemporary informants, the Shoshone buffalo party should have been gathering there. However, on the western side of the Wind River Range, they found "a party of Snakes who had come across the mountains on their autumnal hunting excursion to provide buffalo meat for the winter" (p. 202). In September of the following year, the eastward-bound party under Stuart encountered a party of "Upsarokas, or Crows" on the Bear River, who said that they intended to trade with the Shoshone (p. 289). This Crow party later ran off the trappers' horses. Throughout their trip to the Green River country, the trapping party was in continual fear of the Blackfoot (p. 298). Upon arriving on the Green River on October 17, 1812, they met a party of about 130 "Snakes" living in some 40 "wigwams" made of pine branches (p. 306). The ostensibly peaceful Crow had run off all but one of the horses of this camp and had stolen some women also. The Astoria chronicle, then, documents a situation that appears consistently in later sources: the Shoshone were usually encountered west of the Continental Divide and were continually on the defensive against powerful tribes to the east and north that seemingly entered their hunting grounds at will.

The activities of the early trappers in northern Utah and western Wyoming brought them into contact with a variety of Indian populations, not all of which are easily identifiable. This region is shown by the reports of the fur seekers to be characterized by a great fluidity of internal movement of Shoshone—and Bannock-speaking groups and by frequent entry by other tribes for purposes of war, trapping, and trade. The journal of J. P. Beckwourth gives a vivid, although not wholly reliable, account of the ebb and flow of population in the area under consideration. While camped near the east shore of the Great Salt Lake late in the year 1823, Beckwourth lost 80 horses to the "Punnaks [Bannocks], a tribe inhabiting the headwaters of the Columbia River" (Beckwourth, 1931, p. 60). His party pursued the Bannock to their village, some five days distant, and, after regaining part of the stolen herd, returned to camp to find some "Snake" (p. 61) (Shoshonean-speaking) Indians camped near by. He states that this group numbered 600 lodges and 2,500 warriors. The Indians were friendly and the locale was said to have been their winter camp (ibid.). Three years later, Beckwourth and his party were camped near the same site (today, Farmington, Utah) and encountered 16 Flathead Indians. Shortly thereafter the trappers were attacked by 500 mounted Blackfoot Indians, who were driven off (ibid., p. 66). Two days later, the fur party was joined by 4,000 Shoshone, who aided them in defeating another Blackfoot attack (pp. 70-71). (Beckwourth's population estimates are probably quite exaggerated.)

While Beckwourth's journals are poorly dated, it was no doubt during the late 1820's that his party was attacked near Salt River in western Wyoming by a body of unidentified Indians who, he claims, were 500 strong (p. 86). Shortly thereafter he fell in with friendly "Snake," or Shoshone, Indians. Near their camp were 185 Bannock lodges, with whose occupants the hunters had some difficulties (pp. 87-88). While in this vicinity, the camp of the trappers and the friendly Shoshone was attacked by a Blackfoot party, after which the trappers and Shoshone moved to the Green River (p. 89). At the Green River camp, the combined trapper-Shoshone group was visited by a party of Crow Indians. Beckwourth comments that "the Snakes and Crows were extremely amicable." Beckwourth reported further on Shoshone-Crow relations (p. 108):

At this time the Crows were incessantly at war with all the tribes within their reach, with the exception of the Snakes and the Flatheads and they did not escape frequent ruptures with them [over horses].

That this peace was extremely uneasy and manifestly ephemeral was clearly shown by later developments when the Shoshone, accompanied by some Ute, attacked a Crow trading party, which later mustered support and retaliated (pp. 183-184). However, at an even later date Beckwourth was able to report that 200 lodges of Shoshone had joined forces with the Crow, ostensibly because of the trading possibilities afforded by Beckwourth's presence among the latter (p. 249).

The relations between the Shoshone and Crow during the 1820's apparently were not much unlike those that prevailed at the time of the passages of the Astoria parties. The Crow, although not relentless enemies of the Shoshone, as were the Blackfoot, constituted a constant source of danger. Beckwourth's journals give evidence of amicable relations between the American trappers and the Shoshone, although he described the more bellicose Bannock as "very bad Indians, and very great thieves" (p. 87). Other sources document more serious difficulties with "Snake" Indians. Peter Skene Ogden reported in 1826 that the American trappers had suffered severe losses at the hands of the Snake Indians during the preceding three years (Simpson, 1931, p. 285), but these mishaps probably occurred in Idaho. In 1824, however, Jedediah Smith and Fitzpatrick lost all of their horses to the "Snakes" on the headwaters of the Green River (Alter, 1925, pp. 38-39; Dale, 1918, p. 91), and some members of Etienne Provot's trapping party were killed by "Snakes" in the winter of 1824-25 (Dale, 1918, p. 103).