Quechua had already expanded across wide ranges of the central Andes long before the expansion of the Inca Empire. The Inca were one among many peoples in present-day Peru who already spoke a form of Quechua. In the Cusco region, Quechua was influenced by neighboring languages such as Aymara, which caused it to develop as distinct. In similar ways, diverse dialects developed in different areas, borrowing from local languages, when the Inca Empire ruled and imposed Quechua as the official language.
After the Spanish conquest of Peru in the 16th century, Quechua continued to be used widely by the indigenous peoples as the "common language". It was officially recognized by the Spanish administration and many Spanish learned it in order to communicate with local peoples. Clergy of the Catholic Church adopted Quechua to use as the language of evangelization. Given its use by the Catholic missionaries, the range of Quechua continued to expand in some areas.
In the late 18th century, colonial officials ended administrative and religious use of Quechua, banning it from public use in Peru after the Túpac Amaru II rebellion of indigenous peoples. The Crown banned even "loyal" pro-Catholic texts in Quechua, such as Garcilaso de la Vega's Comentarios Reales.
Despite a brief revival of the language immediately after the Latin American nations achieved independence in the 19th century, the prestige of Quechua had decreased sharply. Gradually its use declined so that it was spoken mostly by indigenous people in the more isolated and conservative rural areas. Nevertheless, in the 21st century, Quechua language speakers number 8 to 10 million people across South America, the most speakers of any indigenous language.
The oldest written records of the language are by missionary Domingo de Santo Tomás, who arrived in Peru in 1538 and learned the language from 1540. He published his Grammatica o arte de la lengua general de los indios de los reynos del Perú (Grammar or Art of the General Language of the Indians of the Royalty of Peru) in 1560.
As result of Inca expansion into Central Chile there were bilingual Quechua-Mapudungu Mapuche in Central Chile at the time of the Spanish arrival. It has been argued that Mapuche, Quechua and Spanish coexisted in Central Chile, with significant biligualism, during the 17th century. Quechua is the indigenous language that has influenced Chilean Spanish the most.
In 2016 the first thesis defense done in Quechua in Europe was done by Peruvian
Carmen Escalante Gutiérrez at Pablo de Olavide University. A Peruvian student,
Roxana Quispe Collantes of the University of San Marcos, completed and defended the first thesis in the language group in 2019; it concerned the works of poet
Andrés Alencastre Gutiérrez and it was also the first non-Spanish native language thesis done at that university.