The Congo River (for a time known as Zaire River) is the largest river in Western Central Africa. Its overall length of 4,700 km (2,922 miles) makes it the secon longest in Africa (after the Nile). The river and its tributaries flow through the second largest rain forest area in the world, second only to the Amazon Rainforest in South America. The river also has the second-largest flow in the world, behind the Amazon, and the second-largest watershed of any river, again trailing the Amazon; its watershed is slightly larger than that of the Mississippi River. Because large sections of the river basin lie above and below the equator, its flow is stable, as there is always at least one river experiencing a rainy season. The Congo gets its name from the ancient Kingdom of Kongo which inhabited the lands at the mouth of the river. The Democratic Republic of the Congo and the Republic of the Congo, both countries lying along the river's banks, are named after it. Between 1971 and 1997 the government of then-Zaire called it the Zaire River.