He was the third son of Odo I, Viscount of Porhoët, and Emma de Léon.
He received as his inheritance, the sparsely populated western Porhoët, in 1116.
[2] In 1128, Alain de Rohan finished constructing his permanent residences and founded the Priory de la Coarde at Castennec for the monks at Redon Abbey, and a priory for Marmoutier Abbey near the château de Rohan.
Alan I married a woman named Villana.
They had two children:[3] This biography of a French peer or noble is a stub.