Mapuche Wooden Mask
Hailing from the southwestern portion of Argentina is a relatively small group of native inhabitants known as the "Araucanos." This is the historical term coined by the early Spanish conquistadors (deriving from the word arauco meaning "clayey water"), but has generally fallen into disregard in favor of the term Mapuche which encompasses a bunch of different ethic groups that share a common heritage. This includes the Picunches, Huilliches, and the Moluche both in Argentina and Chile. Araucanian society is mostly agricultural and large extended-family based with a lonko (like a chief who was generally wealthier) leading the people.
Recently, the Mapuche people have migrated to more urban areas in search for greater economic potential while the traditional area of Araucania remains nearly 80% Mapuche descendants. Roughly 900,000 Chileans and Argentinians currently identify themselves as being of Mapuche heritage. And conflict has been rising over the past few decades over land disputes between the Mapuche people and Chilean-owned forestry companies.
You can check out the Wikipedia page on the Mapuche to learn a little bit more about them, but I really suggest taking a quick look at this paper for the Royal Antropological Institute on the Ethnology of the Araucanos by R.E. Latcham. The paper looks at the culture from the Incan invasion and examines all points of the culture, from what they wore and what they ate to their religious beliefs and the need for witch-doctors.