At the time of the arrival of the first Spaniards to Chile the largest indigenous population concentration was in the area spanning from Itata River to Chiloé Archipelago. In this area indigenous groups practised glade agriculture among the forests. The forests provided firewood, fibre and allowed the production of planks. Agriculture type varied; while some Mapuches and Huilliches practised a slash-and-burn type of agriculture some more labour-intensive agriculture is known to have been developed by Mapuches around Budi Lake (raised fields) and the Lumaco and Purén valleys (canalized fields). Pre-Hispanic agriculture extended as far south as the Guaitecas Archipelago (44° S), were indigenous Chonos cultivated Chiloé potatoes. Tools are known to have been relatively simple. In addition the Mapuche and Huilliche economy was complemented with chilihueque raising. The southern coast was particularly rich in molluscs, algaes, crustaceans and fish.