The Illinois Country (French: Pays des Illinois) — sometimes referred to as Upper Louisiana (French: la Haute-Louisiane; Spanish: Alta Luisiana) — was a vast region of New France in what is now the Midwestern United States. While these names generally referred to the entire Upper Mississippi River watershed, French colonial settlement was concentrated along the Mississippi and Illinois Rivers in what is now the U.S. states of Illinois and Missouri, with outposts in Indiana. Explored in 1673 from Green Bay to the Arkansas River by the Canadien expedition of Louis Joliet and Jacques Marquette, the area was claimed by France. It was settled primarily from the Pays d'en Haut in the context of the fur trade. Overtime, the fur trade took some French to the far reaches of the Rocky Mountains, especially along the branches of the broad Missouri River valley. The French name, Pays des Illinois, means "Land of the Illinois [plural]" and is a reference to the Illinois Confederation, a group of related Algonquian native peoples.