Flag Sticker Saarland region, Germany. Its capital is Saarbrücken. The region of the Saarland was the territory where the Celtic tribes of the treveos and the mediomátricos settled. There was an impressive Celtic fortress in Otzenhausen north of the Saarland. In the S. I a.C. It was part of the Roman province of Gaul Belgium, after the conquest by Julius Caesar in 58 BC. C.