Southern Patagonian Ice Field in the area, among which are the Upsala (765 km), Viedma (978 km) and Perito Moreno (258 km) in the Los Glaciares National Park in Argentina, and the Pío XI Glacier or Bruggen Glacier (1,265 km, the largest in area and longest in the southern hemisphere outside of Antarctica), O'Higgins (820 km), Grey (270 km) and Tyndall (331 km) in Chile. The glaciers going to the west flow into the fjords of the Patagonian channels of the Pacific Ocean; those going to the East flow into the Patagonian lakes Viedma and Argentino, and eventually, through the rivers "de la Leona"
Patagonian Desert known by name are those of the Tehuelche complex. Tehuelches lived as hunter-gatherers and did not practise agriculture in lush valleys found in the desert. In the 18th and 19th centuries the northern part of the desert came under Mapuche influence during a process of Araucanization. Mapuches came to practise horse husbandry in the northern part of the Patagonian steppe. Mapuche tribes came to control trade across the desert and traded with the cities of southern Chile as well as Buenos Aires and the Cuyo Region. From the mid-19th century onwards several Argentine and European settlements, some of them sporadic,