After passing the falls, Lewis regretted leaving the buffalo country because the expedition had been warned by Indians that they would soon leave the region where buffalo were plentiful, and he knew they would sometimes have to fast. On the plains, vast herds of buffalo, deer, and elk, along with roots and berries from edible plants, provided abundant food, but the party could not carry much with them and had to rely on what hunters found as they traveled. Beyond the Tower and into the mountains, conditions reversed, and in the Rockies they lived on very basic subsistence, eating whatever little became available and never enough to satisfy their hunger.