During the century of internecine struggles for dominance among the Northern Christians kingdoms, the County of Portugal, formed the southern portion of the Kingdom of Galicia. At times the Kingdom of Galicia existed independently for short periods, but usually formed an important part of the Kingdom of Leon. Throughout this period, the people of County of Portugal as Galicians found themselves struggling to maintain the autonomy of Galicia with its distinct language and culture (Galician-Portuguese) from the Leonese culture, whenever the status of the Kingdom of Galicia changed in relation to the Kingdom of Leon. As a result of political division, Galician-Portuguese lost its unity when the County of Portugal separated from the Kingdom of Galicia (a dependent kingdom of Leon) to establish the Kingdom of Portugal. The Galician and Portuguese versions of the language then diverged over time as they followed independent evolutionary paths. This began occurring when the Kingdom of Leon and the Kingdom of Castile united and the Castilian Language (known as Spanish) slowly over the centuries began influencing the Galician Language and then trying to replace it. The same thing happened to Astur-Leonese Language to the point where it is greatly reduced or completely replaced by the Castilian (Spanish Language).
By which language was the Astur-Leonese replaced?
Castilian (Spanish Language)