Why did colonial authorities encourage the use of Quechuan languages?

Colonial authorities encouraged the use of Quechuan languages primarily because they served as a convenient and efficient tool for both government administration and missionary activities.1

Following the Spanish conquest, Quechua functioned as a widespread lingua franca across the Andes, having already been established as an administrative medium during the Inca Empire. Because the language was already understood across a vast territory, it allowed colonial officials and missionaries to communicate more easily with diverse Indigenous populations. Missionaries, in particular, utilized the language for evangelization, and at certain periods, they were even required to demonstrate proficiency in it to carry out their work.2341

By adopting and promoting this existing linguistic infrastructure, colonial authorities were able to exert control and facilitate their objectives more effectively than if they had attempted to navigate the region's immense linguistic diversity individually. Consequently, the use of Quechua often led to the displacement of smaller, local Indigenous languages.14