It should be noted that information on the entry of Shoshone or Bannock groups into the buffalo grounds of Montana occurs very early in the historical period in the reports of Lewis and Clark, and also very late in this period. It is true that there is little pertinent historical data on southwestern Montana, but there is a distinct possibility that the Shoshone and Bannock did not cross the Divide annually. Buffalo were found on the upper Snake River prairie until about 1840, and the presence of the Blackfoot in Montana made ventures there risky. It is noteworthy that in the early reservation period the Bannock crossed the Divide into the Big Horn drainage in company with the Eastern Shoshone; the trip through Green River and thus to Wind River was not by any means the shortest route to the buffalo country. On the other hand, informants gave highly detailed information on the trail to the Montana buffalo grounds and showed detailed traditional knowledge of it. Without more continuous historical data such as is available on transmontane hunting patterns in Wyoming, any question of historical changes in hunting itineraries must remain open. From Camas Prairie, contemporary informants say, the buffalo party skirted the southern end of the Sawtooth Mountains and went up the Little Lost River, crossing over to the Lemhi River. They then traveled down the Lemhi and across the Divide via Lemhi Pass. Descending the east side of the mountains, the buffalo party arrived on the Beaverhead River at a point close to Armstead, Montana. They then traveled down the Beaverhead past Twin Bridges to the point where the Beaverhead becomes the Jefferson River and thence downstream to the Three Forks of the Missouri. One informant said that the Beaverhead Valley contained buffalo in earlier times, but by the period preceding the treaty it was necessary to go much farther east. From Three Forks, Montana, the buffalo route followed the present line of U.S. Highway 10 through Bozeman and over Bozeman Pass. The party pressed eastwards until it arrived in the country called Buffalo Heart by the Bannock because a near-by mountain supposedly had the shape of a buffalo heart; this was the fall and winter hunting grounds of the Idaho Shoshone and Bannock. It was near the Yellowstone River between Big Timber and Billings, Montana, though the migratory habits of buffalo and buffalo hunters would dictate considerable movement within the region. The buffalo hunters remained to the west of the Bighorn River and, presumably, they did not encroach too heavily upon the Crow. While the Crow considered the Eastern Shoshone enemies, we have no information on hostilities between them and the Idaho people. The Bannock actually camped with the Crow in the late 1860's and early 1870's.