In the western area of the provinces of Zamora, Salamanca, Caceres, Badajoz and Huelva, there are diverse linguistic enclaves where the Portuguese influence is more than evident. In this article, we review the Portuguese lexicon that has been observed in the dialectal tongues of western Spain. We evaluate the current situation and make reference to the two reasons that explain its presence: historical reasons, in very specific cases, and geographical reasons, in the majority of the border territory.