Lorraine, medieval region, present-day northeastern France. By the Treaty of Verdun (843), it became part of the realm of Lothar I. Inherited by his son Lothar, it became the kingdom of Lotharingia. After Lothar’s death, it was contested by Germany and France and came under German control in 925. In 959 it was divided into two parts, the southern Upper Lorraine and the northern Lower Lorraine. In 1190 the duke of Lower Lorraine took the name of duke of Brabant. With the dissolution of the lower duchy, the upper duchy came to be called simply Lorraine.