Orinoco

The Orinoco River is one of the longest rivers in South America at 2,140 kilometres (1,330 mi). Its drainage basin, sometimes known as the Orinoquia, covers 880,000 km2 (340,000 sq mi), with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the third largest river in the world by discharge volume of water. The Orinoco River and its tributaries are the major transportation system for eastern and interior Venezuela and the llanos of Colombia. The environment in the Orinoco's basin is extremely diverse; it hosts a wide variety of flora and fauna.

Orinoco in "The Pugnacious Peacemaker"
The Ooriinookoo was the border of the Empire of Tawantiinsuuju and the Emirate of the dar al-Harb for the most part, but there were bloody disputes as to the precise boundary.