With approximately 8-9 million speakers, Quechua is the largest surviving indigenous language in the Americas.
It originated in Peru with the Incas, and then due to trade relationships, it spread north to southern Columbia and south to northern Argentina. Quechua is mostly spoken in Peru and Bolivia where it has joined official status with Spanish.
When the Spanish first arrived in the 1500s, Quechua was such an important language that it continued to be widely used. It was officially recognised by the Spanish administration, and Spanish officials learnt it to communicate with the locals.
However, in the 18th century, Quechua was banned as an administrative and religious language, and its use declined. In the 19th century it was reinstated, but by this time the damage had been done and Quechua was no longer seen as a prestigious language. Quechua was made an official language in Peru in 1975, but Spanish is still seen as the language of economic advancement.