2 In the sacred records of Bavaria are many circumstances, but We recall things unknown to you, concerning which the Church and the State may unite in a common joy. For the Christian faith, from the time when its divine seed was sown in the bosom of your country by the care and great diligence of the holy Abbot Severinus, who stands out as the apostle of the country between the Danube and the Alps, and of other preachers of the gospel, sent forth and fixed its roots so deeply that thenceforward it has never been utterly eradicated either by the barbarity of superstition or the revolution and change of public affairs. Wherefore it came to pass about the end of the seventh century, that when Rupert, the holy Bishop of Worms, at the invitation of Theodore, Duke of Bavaria, went forth to stir up and increase the Christian faith in those parts, he found indeed, many, both professors of the faith and others desirous of embracing it, even in the midst of superstition. But that most excellent Prince Theodore himself, inflamed by zeal for the faith, undertook a journey to Rome, and prostrate at the Tombs of the Holy Apostles and, at the feet of the august Vicar of Jesus Christ, first afforded a most noble example of piety and of the union of Bavaria with this Apostolic See, which other excellent princes afterwards religiously followed. At the same time Cardinal Martinianus, Bishop of Sabina, was sent as legate to Bavaria by the Holy Pontiff Gregory IL, who brought aid and assistance in Catholic affairs, with whom were associated Georgius and Dorotheus, both Cardinals of the Roman Church. Not long afterwards Corbinianus, Bishop of Munich, a man renowned for his holiness of life and contempt of the world, who confirmed and increased the effect of the apostolic labours of Rupert by an equal amount of labours, set out to visit the Sovereign Pontiff at Rome.
Source: Officio Sanctissimo (Vatican.va)