The river has its origins high up in the Andes of Peru and Ecuador. Most of this drainage basin (54%) is in Brazil, including the lower part, other portions are parts of Peru, Bolivia, Ecuador, Columbia and a small part of Venezuela. The river also has tributaries from Colombia, Venezuela and Bolivia. The Amazon rainforest is the largest in the world, covering about 8,235,430 km2 with dense tropical forest. Most of the basin is covered by the Amazon rainforest, also known as Amazonia.
The Amazon Basin is one of the world's most important ecosystems.