Guaraní people
In 1919 he moved to Buenos Aires, and two years later his restless spirit led him to the jungles of Caaguazú, where he worked harvesting yerba maté. Absorbed by the rugged and primitive environment, he became interested in the life of the Guaraní people. Cadogan studied, published and became an authority on Mbyá Guaraní, Ava-Guaraní, Pai-tavytera, and Ache-guayaki — various Guaraní tribes living in the forests of eastern Paraguay.