Regions are they a future-oriented frame of country planning? a continuation of the Old Regime past? the new avatar of a mythical timeless space? or each of these things at the same time? This text focuses on the Breton case. The concept of "region" is not understood here in the sense of an administrative unit but as a real social fact, in various sizes: both historical, economic, cultural and social. We will discuss both the myth of eternal Brittany, the long-time history of Brittany and the question of its immateriality.