The Estrela Mountain Dog originated in Portugal's Serra da Estrela mountain range. Although the exact origins of the breed are unknown, one theory suggests that it was the Romans that brought the breed to Portugal when they invaded the Iberian Peninsula. Regardless of how the Estrela came to Portugal, one thing is undisputed – it is one of the ancient breeds in Portugal that still exists today.
Though it is believed that the Estrela Mountain Dog has existed for hundreds of years, the first recorded breed standard was published only in 1922. The first official breed standard was not written until 1933, even then the breed was not widely popular.
Several factors contributed to its minimal numbers in the 1900s. The first factor is the isolation where the Estrela is bred, which meant the breed was not known outside the region. Second, the desire of Portuguese Shepherds to prevent the Estrela dogs from leaving the flocks to mate, which drove them to castrate most of the dog breeds. Third, the disinterest of Serra residents to follow the official breed standard and reluctance to participate in dog shows. Fourth, the Portuguese preference for foreign dog breeds. Fifth, dog showing was simply for the wealthy.
The Portuguese revolution in 1974, in a way, saved the breed from total extinction. It allowed working people to present native dogs in dog shows. With the rise of crime rate after the revolution, the demand for large guard dogs such as the Estrela Mountain dog also increased. Today, the Estrella Mountain dog is still utilised as a working dog but is also becoming known as an ideal family pet.