It is called the Blue line of the Vosges. The peaks of the Vosgian mountains mark the separation of Alsace from the Duchy of Lorraine. Both regions were part of the Holy Roman Empire, but Lorraine became sovereign from 1542 to 1766. German was spoken in the east, Romance in the west with a few exceptions, as in the valley of Riquewihr, where people spoke Welche (Welsch, in German, means foreigner of Latin race). The Rhine became France's border during the Revolution. Today, many Alsatians aim to form a cross-border region within the framework of the European Union.