My mistake, Leon doesn't border on Portugal but is quite close to the Tras-os-Montes region where the Transmontano comes from. That same region was also historically part of the Kingdom of Leon.

I've seen many pics of old black n white, as well as modern day photos of SMs that are clearly unrelated to the newly created overglorified saint/mastiff/fila/neo mix that is the AEPME Mastin Español, that can - in looks and coloration - easily pass for Rafeiros, Transmontanos or even smooth coat Estrelas. It goes to show that appearance can be deceiving when it comes to dog breeds or landraces... the Turkish and Central Asian LGDs maybe very distantly related to those of Iberia, or the Balkans..