 The dynasty got its name from Childebrand's heir, Nibelung I (""The Historian"").Childebrand's immediate descendants held the County of the Vexin in the 9th century.The relationships between the various Childebrands and Nibelungs of the period are rarely attested in primary sources, leaving it to genealogists, prosopographers, and onomasticists to piece together possible lines of descent.