 Originating from the Saalfeld region, he held large estates around Weimar, Jena, and Apolda, possibly stemming from late Duke Burchard of Thringia, whose sons were expelled by King Henry the Fowler in 913.He was probably married to a daughter of the Babenberg duke Poppo of Thuringia, margrave of the Sorbian March, who had been deposed by the East Frankish king Arnulf in 892.William too appeared in the rank of a Thuringian margrave.