Flanders is often portrayed as an area with an important specificity and therefore with a regional identity that is strong, if not irreducible to any sense of belonging to a wider national or European community. However, general public opinion has always varied on the question of what is Flanders and on the criteria that could define its identity. The complexity of the territory was increased by the status of border region whose delimitation and sovereignty were subject to fluctuations due to wars and treaties. This applies particularly to the period concerned i.e. from the Franco-Austrian border treaties in 1769 and in 1779 to the end of the First French Empire in 1815 and the Treaty of Kortrijk in 1820: corrections, revolutions, wars, annexations and departmentalisation shaped and reshaped the Flemish territory. How could this permanent reshaping interact with the allegedly strong identities of the border populations? The observing of the family, social, economic, military, religious or even linguistic practices tends to show the compatibility between different local, provincial, national and international references that create plural identities, in France as well as in the Belgian provinces. The plasticity of these practices and affiliations leads us to deconstruct the Flemish identity that was essentially built afterwards, while it was still in development during the study period and not fully developed before the second half of the 19th century. Thus the measures that claim to permanently establish any identity or boundary, whatever or wherever they may be, should be considered carefully, by historicising the process of identity building. ; La Flandre est souvent présentée comme un espace doté d’une importante spécificité et par là d’une identité régionale forte voire irréductible à des appartenances nationales ou européennes plus amples. Pourtant, les opinions n’ont cessé de varier sur ce que sont les Flandres et sur les critères qui définiraient cette identité. Le statut de régionfrontière soumise à des ...