By 1840, bison (buffalo) had been hunted and trapped to extirpation west of the Continental Divide. The Shoshone and Bannock tribes had established a plains-style culture based on the buffalo on the Snake River plains, but the regional extirpation forced them to organize hunting migrations across the Yellowstone Plateau. These tribes established a route that became known as the Bannock Trail. The route began at Camas Meadows in Idaho, went over Targhee Pass, followed the Madison River basin, went over the Gallatin Mountains near Mount Holmes, down Indian Creek to the Gardner River, through Snow Pass to Mammoth Hot Springs, up Lava Creek, through the meadows of Blacktail Deer Creek, to the Bannock Ford crossing of the Yellowstone River near Tower Fall, up the Lamar Valley, and over the Absaroka Range into the Clarks Fork Valley. From there, Bannock and Shoshone (often with Flathead and Nez Perce) would choose between the Yellowstone Valley and the Wyoming Basin to hunt bison. For forty years ending in 1878 with the Bannock War, tribes used the Bannock Trail for access to drainages such as the Madison, Gallatin, Yellowstone, Stillwater, Clarks Fork, and Shoshone valleys, and through them to a more distant arc of buffalo ranges.