The County of Bar, later Duchy of Bar, was a principality of the Holy Roman Empire encompassing the pays de Barrois and centred on the city of Bar-le-Duc. It was held by the House of Montbéliard from the 11th century. Part of the county, the so-called Barrois mouvant, became a fief of the Kingdom of France in 1301 and was elevated to a duchy in 1354. The Barrois non-mouvant remained a part of the Empire. From 1480, it was united to the imperial Duchy of Lorraine.

Bar-le-Duc, formerly known as Bar, is a commune in the Meuse département, of which it is the capital. The department is in Grand Est in northeastern France.