High Quality Content by WIKIPEDIA articles! The House of Rohan is a family of viscounts, later dukes and princes, coming from the locality of Rohan in Brittany. Their line descends from the viscounts of Porhoët and said to trace back to the legendary Conan Meriadoc. Through the Porhoët, the Rohan are related to the Dukes of Brittany, with whom the family intermingled again in after its inception. They developed ties with the French and English royal houses as well, and played an important role in French and European history.