Description of a Pyrenean Mastiff.

Massive flock-guarding dogs arrived on the Iberian Peninsula over 30 centuries ago. Cargos of Assyrian and Sumerian-type dogs were traded around the Mediterranean by the Phoenicians. Many of these dogs were left in Spain, where they found ample employment with the great flocks. As they spread throughout the peninsula, the dogs developed several regional variations. Moving north into the ancient kingdom of Aragon, the Pyrenean Mastiff was born.

Until nearly 1500, Spain was divided into several small, ever-changing, often warring, principalities. But a most civilized system of sheep raising developed that transcended political and economical uncertainties.

The Trashumante, or the formal mass migration of flocks to and from grazing grounds, paralleled the history of the Pyrenean Mastiff. The Visigoth King Eurico created the first regulations for these migrations in 504 AD, which continued through the 18th century. The routes (always north and south from the mountains to the lowlands) for each grand flock were formally delineated, and the shepherds, sheep and sheepdogs were allowed to cross political barriers and to supersede wars in then-search for grass. The sheep were divided into herds of 1,000 head, each assigned a shepherd and five mastins—no more—with the canines each receiving the same food allotment as each human. The dogs protected the flocks from wolves and bears and were highly esteemed.