This essay proposes, first, a revision of the concept of frontier as concerns limen, “threshold”, going beyond the concept of limes, or boundary. It is proposed that this threshold extends chronologically beyond the 15th century, surpassing the contours of Europe in its American projection, from Mexico to Chile. Secondly, the publication of G. Guarda’s book La Edad Media de Chile (The Middle Ages of Chile) gives us the opportunity to reflect on this last frontier and its characteristics. Finally, in a path that Guarda does not explore, this essay proposes that the tradition of Canto a lo Humano in Chile, part of the identity of the peasant communities of the Central Valley region, has “medieval echoes”.