In the La Tene period Salzburg was an administrative center of the Celtic kingdom of Noricum. After the Roman invasion 15th AD, the population of the city on the hills was due to the city planning of the Roman moved into the area of todays´s old town. Since Emperor Claudius, the new city, as Municipium Claudium Iuvavum, was one of the main cities of the Roman province of Noricum. After giving up the province Noricum 488 AD, at the beginning of the mass migration, a part of Romano-Celtic population remained in the country. In the 6th century, the conquest was followed by the Bavarians. Bishop Rupert got the remains of the Roman city as a present from Duke Theodoas of Bavaria around 696 AD to evangelize the country in the east and southeast.