A line segment on a graph would be any line that isn't continuous. It would have dots on the ends instead of arrows. Is that what you're asking?
Some of the most populous ones are the Guarani, Tikuna, makuxi. The majority of the tribes were assimilated in 2019-2010. The country is going through a fight in the courts with president Bolsonaro on the legitimacy of some of the smaller tribes, and the land they own.
