Around 100AD, the Romans came to conquer Britain and the Isles. Some of the Brigantes clans aligned with the invaders, but not all. Those that fought were conquered, taken, and dispersed through the Roman empire.
A group of Celtic witches, widowed and stolen from their homes, created a curse to protect themselves from men who would do them harm.
Their spell would transform a man into a supernatural warrior, guided by the magick of Fate and the manifestation of a powerful wolf spirit. He would have the senses of a wolf, the strength of ten men, long life and good health.
The price of this supernatural power was enslavement to the moon. All werewolves were transformed under the light of a full moon and had no choice but to remain in animal form until the moon released them.
The widows bound themselves to these warriors with a hundred-year-bond, extending the protection of the curse to their own bodies.
And that curse created the Moonbound race.