The mountain chain that runs the length of South America is the Andes Mountains. This extensive range stretches over 7,000 kilometers (about 4,300 miles) and is recognized as the longest continental mountain range in the world. The Andes are known for their diverse ecosystems, from tropical rainforests to arid deserts. They are home to various indigenous cultures and significant cities like Quito and La Paz and are important for agriculture and mineral resources.