In this book, firstly, a description of the four groups of border languages or dialects of Extremadura is carried out, to which other elements of analysis and discussion of great validity in our days have been added: the survival of the spoken, linguistic attitudes, the normalization and standardization of the fala, dialect affiliation, etc. A second part of this work is dedicated to studies of a historical nature. In this way, thanks to the documentation found, the extension of the Portuguese language in the Valencia de Alcántara region has been determined until the 16th century, the origin of the Portuguese-speaking populations of the line or the presence of the Portuguese language in the documentation. medieval.