During the post-Roman centuries of Germanic migration and settlement, the region afterwards included in the Diocese of Bamberg was inhabited for the most part by Slavs. The town, first mentioned in 902, grew up by the castle (Babenberch) which gave its name to the Babenberg family. On their extinction it passed to the Saxon house. The area was Christianized chiefly by the monks of the Benedictine Fulda Abbey, and the land was under the spiritual authority of the Diocese of W�rzburg.
In 1007, Holy Roman Emperor Henry II made Bamberg a family inheritance, the seat of a separate diocese. The emperor's purpose in this was to make the Diocese of W�rzburg less unwieldy in size and to give Christianity a firmer footing in the districts of Franconia, east of Bamberg. In 1008, after long negotiations with the Bishops of W�rzburg and Eichst�tt, who were to cede portions of their dioceses, the boundaries of the new diocese were defined, and Pope John XVIII granted the papal confirmation in the same year. Henry II ordered the building of a new cathedral, which was consecrated May 6, 1012. The church was enriched with gifts from the pope, and Henry II had it dedicated in honor of him. In 1017 Henry II also founded Michaelsberg Abbey on the Michaelsberg ("Mount St. Michael"), near Bamberg, a Benedictine abbey for the training of the clergy. The emperor and his wife Cunigunde gave large temporal possessions to the new diocese, and it received many privileges out of which grew the secular power of the bishop. Pope Benedict VIII during his visit to Bamberg (1020) placed the diocese in direct dependence on the Holy See. For a short time Bamberg was the centre of the Holy Roman Empire. Henry and Cunigunde were both buried in the cathedral.
From the middle of the 13th century onward the bishops were princes of the Empire and ruled Bamberg, overseeing the construction of monumental buildings. In 1248 and 1260 the see obtained large portions of the estates of the Counts of
