The indigenous Guaraní had been living in eastern Paraguay for at least a millennium before the arrival of the Spanish. Western Paraguay, the Gran Chaco, was inhabited by nomads of whom the Guaycuru peoples were the most prominent. The Paraguay River was roughly the dividing line between the agricultural Guarani people to the east and the nomadic and semi-nomadic people to the west in the Gran Chaco. The Guarcuru nomads were known for their warrior traditions and were not fully pacified until the late 19th century. These indigenous tribes belonged to five distinct language families, which were the bases of their major divisions. Differing language speaking groups were generally competitive over resources and territories. They were further divided into tribes by speaking languages in branches of these families. Today 17 separate ethnolinguistic groups remain.