The Matis people have not been "discovered" in the sense of being found by outsiders. They have lived in their traditional territory in the Amazon rainforest of Brazil for centuries, likely for thousands of years.

It's important to recognize that the term "discovered" can be problematic when talking about indigenous communities. It implies that they were previously unknown or unimportant, which is not true. Indigenous people have lived and thrived in their territories for millennia, with rich cultures and traditions long before any contact with outsiders.

Instead of "discovered," we should talk about the first contact between the Matis and outsiders. This occurred in the early 20th century, with the arrival of rubber tappers and missionaries.

However, it's crucial to remember that contact with outsiders has often had a devastating impact on indigenous communities, bringing disease, displacement, and cultural disruption.