Quechua

Quechua, usually called Runasimi ("people's language") in Quechuan languages, is an indigenous language family spoken by the Quechua peoples, primarily living in the Peruvian Andes and highlands of South America. Derived from a common ancestral language, it is the most widely spoken language family of indigenous peoples of the Americas, with a total of probably some 8–10 million speakers. Approximately 25% (7.7 million) of Peruvians speak a Quechuan language. It is perhaps most widely known for being the main language family of the Inca Empire. The Spaniards encouraged its use, so Quechua ultimately survived and variants are still widely spoken today, being the co-official language of many regions and the second most spoken language in Peru.

Quechua in "The Pugnacious Peacemaker"
Ketjwa was the official language of the Empire of Tawantiinsuuju. In 1941, Ib Scoglund, a Vinlander judge for the International Court for the Continent of Skrelleland, learned it in a crash course for his diplomatic mission. His valet Eric Dunedin was not so good at it.

Quechua in Through Darkest Europe
Kechwa was a language spoken by people in a large region of the Sunset Lands.