In his time, he was known in France as a chronologist. Pezron traced Welsh and Breton origins  to the Celts of ancient writers, and traced the Celts further to eponymous hero-patriarchs from Gaul to Galatia.
During that era, he gained recognition in France for his work on dating events. Pezron linked the origins of the Welsh and Bretons to the writings of ancient Celtic authors, and subsequently examined the ancestral heritage of the Celts through mythical founder-chiefs from Gaul to Galatia.