Adrabaecampi is the scholarly transliteration into Latin of Ptolemy's Adrabaikampoi, a tribe, he says, of greater Germany, dwelling on the north bank of the Danube south of the Gabreta Forest after the Marcomanni and Sudini. That is all history tells us. Claudius Ptolemaeus, given contemporary German styling, in a 16th century engraved book frontispiece Claudius Ptolemaeus (Greek: Κλαύδιος Πτολεμαῖος; c. ... Length 2,888 km Elevation of the source 1,078  m Average discharge 30 km before Passau: 580 m³/s Vienna: 1,900 m³/s Budapest: 2,350 m³/s just before Delta: 6,500  m³/s Area watershed 817,000  km² Origin  Black Forest (Schwarzwald-Baar, Baden- Württemberg... The Gabreta Forest is an ancient forest mentioned by the Greek geographers, Strabo and Ptolemy. ... The Marcomanni were a Germanic people, probably related to the Suebi or Suevi. ...