What language is the mother tongue of many Peruvians and Ecuadorians?

The mother tongue of many Peruvians and Ecuadorians is Quechua.

Quechua is an indigenous language spoken by millions of people in the Andes region of South America. It is the second most widely spoken native language in South America, after Spanish. Quechua is spoken in Peru, Bolivia, Ecuador, Chile, Argentina, and Colombia. There are many different dialects of Quechua, and not all of them are mutually intelligible.

In Peru, Quechua is spoken by about 13 million people, making it the most widely spoken language in the country after Spanish. In Ecuador, Quechua is spoken by about 2 million people, making it the third most widely spoken language in the country after Spanish and Shuar.