Knowledge of its existence ended towards the 17th century. Its triangle-shaped borders are formed by the Madre de Dios river to the Northwest, in what today is Peru, the Beni river to the Southeast, in what today is Bolivia, and the first andean foothills to the south. A triangle of around 80,000 square kilometers that since then and until this day is one of the largest and most biodiverse biological corridors in the world.
This life heartland cut in half by what today is the Peru-Bolivia border, is part of the Antisuyu, one of the four Inca kingdoms. Its ancestral inhabitants have millenary cultural inheritance from the Mollo ancestral culture and today’s Kallawaya.
The arrival of the Jesuits in the 17th century brought about great changes in the region. Some tribes were subdued and relocated, evangelized and converted. Others were able to run into the forest and remain less perturbed by the radical cultural changes and aberrations brought about by the now colonizing order.
Among the tribes that inhabited the Irimo nation that are mentioned by the Jesuit texts are the Chiman, Mosetén, Leco, Tacana, Uchupiamona, Araona, Esse Ejja and Toromona. This last one are the ones that are still living in voluntary isolation, uncontacted, inside of the forest. Many of the mentioned tribes are recognized today by the new constitution of the Plurinational State of Bolivia, though this recognition is mostly only symbolical. As far as territories go, only a small fraction of what was Irimo has been titled to these tribes, the rest, is either a national park, or is being exploited and invaded.