The Arauca is typical of the rivers that flow east across the Llanos Orientales starting as a swift mountain stream and becoming wider and slower as it crosses the plains. It starts high in the Andes, in the Páramo del Almorzadero at over 4,000 meters above sea level. Initially it is called the Chitagá, it receives inflows from the Carabo and the Cacota, and then twists its course towards the east joining with the Culaga and the Bochaga. At which point its name changes to the Margua. The Negro, the Colorado and the San Lorenzo then flow into it. From the right bank come the Cubugón and the Cobar from the Sierra Nevada de Chita. In this stretch the Tunebo Indians call the river the Sarare. Now flowing across a flat zone, it divides to form the Charo Island. Serving as the demarcation line between Colombia and Venezuela for 296 kilometers of border, on the right side the rivers Royata, Bojabá and Banadía flow in, whereas on the left the Cutufí river enters. From this point it takes the name Arauca in tribute to the Araucana tribe who inhabited the mountain ranges of the upper course and belonged to the great Arawak family. Now in the savannas of the Llanos Orientales it often becomes a braided river with the main course splitting to form the subsidiary channels, such as the one called Agua Limón. Various subsidiary channels are extensively used for transportation from the town of Arauca down to its mouth on the Orinoco. The course of the river is 80 percent navigable in small boats.