This paper explores the influence of conflicting scale-making projects of boundary preservation on multilingual histories of indigenous Quechua and Aymara speakers in Puno, Peru. The paper presents a scalar analytic method to Quechua-Aymara language contact. Linguistic difference is the scalable metric that generates two conflicting scalar projects. One underscores ethnolinguistic difference, the other shared indigenous heritage. Both scalar projects affect Quechua-Aymara social and linguistic practices, and discourses about multilingual indigenous histories.