With the near disappearance of wild herds of livestock and the inexorable movement of settlers further south into the Pampas, Mapuche and Tehuelche groups found it increasingly difficult to maintain their way of life. Indigenous raids - called malones - on estancias and white settlements became ever more frequent, and debate raged in the 1870s as to how to solve the "Indian Problem". Two main positions crystallized. The one propounded by Minister of War, Alsina , consisted of containment, using a line of forts and ditches, and aimed at a gradual integration of the indigenous tribes. The second, propounded by his successor, General Julio Roca , advocated uncompromising conquest and subjugation. An increasingly powerful and self-confident Argentina could, now the Paraguayan war had ended and the Federalist rebellions of the early 1870s had been stamped out, concentrate on territorial expansion to the south. Indeed, with the same clarity as the policy of Manifest Destiny in the United States, the likes of Roca viewed that herein lay the future of the Argentine nation.

Roca led an army south in 1879, and his brutal Conquest of the Desert was effectively over by the following year, leaving over 1300 indigenous dead and the whole of Patagonia effectively open to settlement. Roca was heralded as a hero, and swept to victory in the 1880 presidential election on the back of his success. He believed strongly in a highly centralized government and consolid ated his power base by using the vast new tracts of land as a system of patronage. With the southern frontier secure, he could, from the mid-1880s, back campaigns to defeat indigenous groups in the Chaco , and thus stabilized the country's northern frontier with Paraguay.