This article explores how informal indigenous slave communication networks developed and were maintained in sixteenth-century Castile, as men and women served as witnesses or sources of information for those indigenous slaves initiating lawsuits to gain their freedom. Based on dozens of lawsuits in the section Justicia of the Archive of the Indies (Seville, Spain), I argue that the distinct oral communication channels formed by indigenous men and women living in different cities and towns of Castile constituted an important element of litigation suits, before, during and after a sentence was reached or the lawsuit ended. In the heart of the Spanish empire –Castile– slaves and freedmen and women inside and outside of the legal “courtroom” engaged with legal discourse about what it meant to be identified or to identify oneself as an indio (person of the Spanish Indies).Este artículo explora las intrincadas redes indígenas, el cómo y el porqué de la participación de hombres y mujeres como testigos en juicios iniciados por esclavos indígenas por su libertad, y la formación de comunidades informales entre ellos en la Castilla del siglo xvi .Basado en docenas de litigios encontrados en la sección Justicia del Archivo General de Indias, el texto analiza los circuitos de comunicación entre esclavos y libertos queconstituyeron una dimensión poderosa de la litigación, antes, durante y después de laconclusión de un juicio. En el corazón del imperio –Castilla– los indígenas esclavizadosse involucraron informal y formalmente en el discurso legal sobre lo que significaba seridentificado como “indio”.