It is important to note that the current région of Lorraine is larger than the historical duchy of Lorraine which gradually passed under French sovereignty between 1737 and 1766. The modern région includes provinces and areas that historically were separate from the duchy of Lorraine proper:
- Barrois
- Three Bishoprics
- several small principalities which were still part of the Holy Roman Empire at the time of the French Revolution
Some people consider that the traditional province of Lorraine is limited to the duchy of Lorraine proper, while other people consider that it includes Barrois and the Three Bishoprics. The Three Bishoprics were non-contiguous territories around Metz, Verdun, and Toul which were detached from the Holy Roman Empire in the 16th century and passed under French sovereignty.
The case of Barrois is the most complicated: the western part of Barrois (west of the Meuse River), known as Barrois mouvant , was detached from the rest of Barrois in the early 14th century and passed under French sovereignty. On the other hand, the largest part of Barrois (east of the Meuse River) was a duchy (Duchy of Bar) part of the Holy Roman Empire and united with the duchy of Lorraine in the 15th century by the marriage of the duke of Bar, René I of Naples, with the daughter of the duke of Lorraine, Isabella. Thus the duchies of Bar and Lorraine were united under the same duke, although formally they kept separate existence until their incorporation into France in 1766.
When French régions were created in the middle of the 20th century, it was decided to gather Barrois, Three Bishoprics, and Lorraine proper into a single region. Barrois was too small to become a région in its own right, while the Three Bishoprics were a territory without any real unity. It was decided to call the région "Lorraine" only, without mention of Barrois, the Three Bishoprics, or any of the small principalities formerly part of the Holy Roman Empire.
