Oddly, I came across these postcards whilst in the midst of an image search for "The Land Leviathan," as in the book by Michael Moorcock.1
There are a few more here.
They are of the Selk'nam, also, Ona, an indigenous people who dwelt on the Tierra del Fuego until the beginning of the 20th century, when western culture quietly disposed of them.
I don't have a whole lot to say about them, other than that they are quite striking visually, and that I think you should look at them. And that it never ceases to amaze how something so authentically otherworldly to our modernish eyes can exist, or existed, right under our noses.
1 Fat was reading this very book. He had dared me, in a way, to guess which edition, according to cover art, he had purchased. Aware only of the DAW edition's art, I was forced to seek what other options were available.