Poppo, a Babenberg, is the younger brother of Henry of Franconia.
They also had a younger brother named Egino.
All three may have been the sons or grandsons of Poppo (I) of Grapfeld.
Poppo had replaced Radulf II in the Sorbian March no later than 880.
In that year, the Daleminzi, Bohemians, and Sorbs threatened to invade Thuringia and burn the German-allied Slav districts.
Poppo's subsequent expedition against them is recorded in three different variations in the three different manuscript traditions of the Annales Fuldenses.
He may or may not have led the Thuringii in this campaign, but he was certainly victorious.
The reasons behind Poppo's battles in 882, 883, and 884 are unknown.
In the former year, he and the Thuringii had instigated a war with Saxons under Egino and had been defeated.
In 883, he again fought his brother Egino, who was recorded as a co-duke of the Thuringii, and was defeated savagely and forced to retreat with only a few men.
Poppo is deprived of his offices and titles in 892.
According to Regino of Prüm, Poppo had advised Arno, Bishop of Würzburg, to undertake the expedition against the Slavs on which he was killed earlier that year.
Because Poppo is replaced in Thuringia by Conrad and Arno is replaced by Rudolf, both Conradines, it has been supposed that King Arnulf was merely patronizing one family over another: the Conradines and Babenbergers will be feuding shortly afterwards.
On the other hand, Poppo may have been punished for the ill-advised campaign of Arno.
