The rivers belonging to this inland drainage system are the Vermejo, San Juan and Desaguadero, with their affluents, and their southward flow can be traced from about 28° S.
Some of the principal affluents are the Vinchina and Jachal, or Zanjon, which flow into the Vermejo, the Patos, which flows into the San Juan, and the Mendoza, Tunuyan and Diamante which flow into the Desaguadero, all of these being Andean snow-fed rivers.
The first attempt to penetrate by way of the river Plate and its affluents inland, with a view to effecting settlements in the interior, was made in 1526 by Sebastian Cabot.
The Am, the, Sane (which rises in the Faucilles and in the lower part of its course skirting the regions of Bresse and Dombes, receives the Doubs and joins the Rhone at Lyons), the Ardche and the Gard are the affluents on the right; on the left it is joined by the Arve, the Isre, the Drme and the Durance.
The principal affluents are the AriCge, the Tarn with the Aveyron and the Agout, the Lot and the Dordogne, which descends from Mont Dore-lesBains, and joins the Garonne at Bec-dAmbez, to form the Gironde.