Río Biobío
Troops of the Inca Empire are reported to have reached Maule River and had a battle with Mapuches from Maule River and Itata River there. The southern border of the Inca Empire is believed by most modern scholars to be situated between Santiago and the Maipo River or somewhere between Santiago and the Maule River. Spanish chroniclers Miguel de Olavarría and Diego de Rosales claimed the Inca frontier laid much further south at the Bío Bío River. While historian José Bengoa concludes that Inca troops apparently never crossed Bío Bío River, chronicler Diego de Rosales gives an account of the Incas crossing the river going south all the way to La Imperial and returning north through Tucapel along the coast.