In the eighteen forties, eighteen fifties, and eighteen sixties, emigrants made the trek to California in one of the largest migrations in American history, traveling on foot or in wagons more than half the distance across the United States by crossing the Great Plains, the Rocky Mountains, the Great Basin, and the Sierra Nevada mountains to reach their promised land. In the Humboldt River valley, the trail shifted a little north or south each year to avoid the dusty track of the previous year, and land there may once have shown its ruts. The early history of the valley also includes the native Indian tribes who lived along the river, mainly Western Shoshone and Paiute, together with earlier hunter-gatherer people who had lived in the area at least eight thousand years before the wagon trains, which native peoples called "dust snakes," came through and changed these ancient cultures forever.