The export of cattle and mules from the Argentine plains to Peru was fully established by the close of the sixteenth century, and it seems to have continued without interruption ever since. Upper Peru is, however, not the only market on which the Argentine breeders lived. At the end of the eighteenth century D'Azara demanded that they should permit the sale of horses and mules to Brazil, for use in the mines. The cattle traffic with Portuguese territory had not then assumed the form of a regular commerce, and the Brazilians made raids on the north-eastern provinces for the animals they needed--60,000 a year, D'Azara says.[21] The export of cattle to Paraguay and Misiones was, on the other hand, of substantial economic importance in the eighteenth century. Before the Revolution, Rengger says, as many as 200,000 head of cattle passed yearly from Corrientes to Paraguay, which paid for them in _mate_ and tobacco.[22] This trade was kept up intermittently in the nineteenth century. The exports from Corrientes were especially important at the time when the Paraguay stock was reconstituted after the war (40,000 head of cattle in 1875). [21] _Memorias sobre el estado rural del rio de la Plata en 1801, Escritos postumos de D. Felix de Azara_, published by D. Augustin de Azara (Madrid, 1847). [22] A. Rengger, _Reise nach Paraguay in den Jahren 1818 bis 1826_ (Aarau, 1835). Finally, the Chilean market was opened to the Argentine breeders about the middle of the nineteenth century. In the time of Martin de Moussy the convoys of cattle to Chile were so numerous that the lucerne fields of both slopes were stripped bare at the very beginning of the season; and they were rented at a high price.[23] Not only the mining provinces of the north, but central Chile also, bought Argentine cattle. The opening of the Chilean market was followed by a remarkable expansive movement in the pastoral colonization of Argentine territory. We can follow the progress of this not only in Martin de Moussy's book, but in all contemporary works of travel. Its chief theatres are the provinces of San Luis and of Santiago del Estero, north of the Rio Dulce, where Hutchinson, in particular, describes the activity of the ranches.[24] Finally, after the Pacific War (1880) the nitrate district, taken from Bolivia and Peru by Chile, received a great influx of population, and works sprang up in the midst of the desert. The nitrate fields, wholly barren and doomed, under their shroud of grey dust, to an unalterable desolation, became at once one of the chief centres of consumption for Argentine stock.