The Saarland (, ; ) is a state of Germany in the south west of the country. With an area of and population of 990,509 in 2018, it is the smallest German state in area apart from the city-states of Berlin, Bremen, and Hamburg, and the smallest in population apart from Bremen. Saarbrücken is the state capital and largest city; other cities include Neunkirchen and Saarlouis. Saarland is mainly surrounded by the department of Moselle (Grand Est) in France to the west and south and the neighboring state of Rhineland-Palatinate in Germany to the north and east; it also shares a small border about long with the canton of Remich in Luxembourg to the northwest. Having long been a relatively small part of the long-contested territories along the Franco-German linguistic border, Saarland first gained specific economic and strategic importance in the nineteenth century due to the wealth of its coal deposits and the heavy industrialization that grew as a result. Saarland was first established as a distinct political entity in 1920 after World War I as the Territory of the Saar Basin, which was occupied and governed by France under a League of Nations mandate. Saarland was returned to Nazi Germany in the 1935 Saar status referendum. Following World War II, the French military administration in Allied-occupied Germany organized the territory as the Saar Protectorate on 16 February 1946. After the 1955 Saar Statute referendum, it joined the Federal Republic of Germany as a state on 1 January 1957. Saarland used its own currency, the Saar franc, and postage stamps issued specially for the territory until 1959. History Before World War I The region of the Saarland was settled by the Celtic tribes of Treveri and Mediomatrici. The most impressive relic of their time is the remains of a fortress of refuge at Otzenhausen in the north of the Saarland. In the 1st century BC, the Roman Empire made the region part of its province of Belgica. The Celtic population mixed with the Roman immigrants. The region gained wealth, which can still be seen in the remains of Roman villas and villages. Roman rule ended in the 5th century, when the Franks conquered the territory. For the next 1,300 years the region shared the history of the Kingdom of the Franks, the Carolingian Empire and the Holy Roman Empire. The region of the Saarland was divided into several small territories,