According to the region's founding legend, Zacian (and Zamazenta) arrived with the two brothers who came from across the sea to become Galar's first kings. If one rejects this tale, it remains on firm historical ground that, as long as the region had its name, Zacian has been known as the Sword of Galar.

The companion of the elder line of diarchs, Zacian served for over a thousand years as a beloved symbol of the Galarian state and the backbone of its military. It was occasionally whispered during periods of civil war that the 'elder line' in truth descended from the younger brother, but had usurped primacy in the diarchy with Zacian's assistance. Monarchy is generally connected with powerful pokemon, but usually this took the form of breeding the strongest in the realm and being passed down with the throne, not of immortal legendary individuals. But Zacian maintained its bonds from trainer to trainer without complaint, at most occasionally intervening in succession struggles between siblings; whoever it liked more inherited the throne.

When forced to choose between King and Country, Zacian chose the King, and all the pokemon in the realm could not bring it down. But status could accomplish what damage could not; after Zacian was lured into the weald, it was induced to fall into a deep slumber. There were brief experiments during the revolution at replacing Zacian with Arcanine, but its fire melted any sword it held in its mouth, so the idea was soon forgotten.

It is said that Zacian will awaken in Galar's time of need, that a worthy trainer shall appear before and awaken it. But whether that trainer will be a deposed pretender or a young pokedex holder remains (at least for a few more months) an open question.