From as early as 10,000 B.C. until the late 19th century, the Lake District was occupied by many different Mapuche communities. In the 17th century, the Catholic church sent missionaries to convert and educate Mapuches, which is evident by the old chapels in the region. Since the arrival of Europeans, many Mapuches have migrated over to what is now the Chilean side of the Andes because of encroachments on their land by European settlers. In the 1860s, the Chilean government pushed for pioneers to settle near the Lake District, which led more Mapuches to cross over the mountains. The migration of Mapuches and the increasing presence of Chileans in the region worried the Argentine government, which began its military campaign, the Conquest of the Desert. General Julio Roca, who led the conquest, believed the Mapuches were occupying some of the most fertile lands in the country, which he and the government wanted to populate with European immigrants and their descendants. The government encouraged Europeans to immigrate by offering them free land, which led to the creation of communities with large Welsh, British, and German populations. Simultaneously, the Conquest of the Desert was a genocidal campaign that killed off many of the Mapuches or forced them to migrate over the Andes into Chile. Much of the land in the Lake District was still unexplored, but tensions between the Chilean and Argentine governments rose in the 1860s as both countries wanted to claim as much land as they could. The conflict was peacefully resolved in 1902 by the British King, Edward VII, who created the border by dividing several of the lakes in half.
In 1934, the Argentine government established Parque Nahuel Huapi as the country's first national park and many other parks were created in the Lake District following that. Shortly after World War II, Argentina became a haven for tens of thousands of Nazis who were fleeing trials and imprisonment in Europe. The lake district was particularly attractive to many of the Nazis because of its resemblance to the Swiss Alps. In 1995, Erich Priebke, a Nazi who had lived freely in Bariloche for 50 years following the war, was arrested and extradited to Italy, where he was eventually sentenced to life in prison. Many āNazi huntersā still scour the Lake District today looking for more war criminals to arrest.