On May 20th they reached the yellowish waters of the Musselshell River. A short distance beyond this Captain Lewis caught his first view of the Rocky Mountains, one of the goals toward which they were tending. Along the Musselshell the country was covered with wild roses and small honeysuckle, but soon after they came into a region that was very bare and dry, where both game and timber were scarce, the mosquitoes annoying, the noonday sun uncomfortably hot, and the nights very cold. The Missouri River, along which they were still traveling, was now heading to the southwest. They were near the border of the present state of Idaho when they passed several old Indian camps, most of which seemed to have been deserted for five or six weeks. From this fact they judged that they were following a band of about one hundred lodges, who were traveling up the same river. They knew that the Minnetarees of the Missouri often traveled as far west as the Yellowstone, and presumed that the Indians ahead of them belonged to that tribe. There were other evidences of the Indians. At the foot of a cliff they found the bodies of a great many slaughtered buffaloes, which had been hunted after the fashion of the Blackfeet. Their way of hunting was to select one of the most active braves, and disguise him by tying a buffalo skin around his body, fastening the skin of the head, with ears and horns, over the head of the brave. Thus disguised the Indian would take a position between a herd of buffalo and the precipice overlooking a river. The other hunters would steal back of the herd, and at a given signal chase them. The buffaloes would run in the direction of the disguised brave, who would lead them on at full speed toward the river. As he reached the edge he would quickly hide himself in some crevice or ravine of the cliff, which he had chosen beforehand, and the herd would be left on the brink. The buffaloes in front could not stop being driven on by those behind, who in their turn would be closely pursued by the hunters. The whole herd, therefore, would usually rush over the cliff, and the hunters could take their pick of hides and meat in the river below. This method of hunting was very extravagant, but at that time the Indians had no thought of preserving the buffaloes. One of the rivers Lewis passed in this region he named the Slaughter River, on account of this way of hunting.