The noble family originally resided in southwestern Bavaria at the castle of Ambras near Innsbruck, controlling the road to the March of Verona across the Brenner Pass, at Dießen am Ammersee and Wolfratshausen. One Count Rasso ("Rath") is documented in Dießen, who allegedly fought against the invading Magyars in the early 10th century and established the monastery of Grafrath. By their ancestor Count Palatine Berthold of Reisensburg, a grandson of the Bavarian duke Arnulf the Bad, the Andechser may be affiliated with the Luitpolding dynasty. Berthold appears a fierce enemy of King Otto I of Germany and was blamed as a traitor at the 955 Battle of Lechfeld against the Hungarians. He probably married a daughter of Duke Frederick I of Upper Lorraine; his descendant Count Berthold II (d. 1151), from about 1100 residing at Andechs, is credited as the progenitor of the comital dynasty.