This map depicts cities founded by Valdivia. It also situates the fictional location of the cave of Ñamku, which I imagine to be in a present day park named Nahuelbuta, on the summit of a mountain on the coastal range which contains some of what little is left of virgin forest.
Important rivers are also depicted. Of these, the Bío Bío became the de facto boundary between Spanish Chile and the lands of the Mapuche, during the 300 or so years that the see-saw conflict between them lasted.
For a summary of this conflict, see: Arauco War, in Wikipedia. Interestingly, this article states that but for fears that other nations might occupy Chile, the Spanish might have abandoned it in the late 16th century, as not worth the war. The reader might note that, of present day Chile, the third of it north of Santiago composes the Atacama Desert, largely uninhabitable, and considered worthless until the discovery of its minerals (nitrate, copper, and etc.), while the third south of the Bío Bío was Mapuche until the latter part of the 19th century … all of which gives credit to the idea of the abandonment of this distant land … which might lead one wildly to speculate as to what would have happened if the Mapuche actually won their war….