The dynasty began with Otakar I, probably a son or son-in-law of Aribo (c.850909), margrave in Pannonia under King Arnulf. Otakar was Count of Steyr in the Traungau, in what is today Upper Austria. Together with Margrave Luitpold, he may have been killed at the 907 Battle of Pressburg. His descendant Ottokar I (died 1064), Count in the Chiemgau, became ruler of the Carantanian march in 1056.