Having both Saxon and Bavarian ancestry, the Supplinburg dynasty was a political opponent of the Salian dynasty and the House of Hohenstaufen. Disputes arose with Duke Frederick II when he refused to hand over property to Lothair, which the king considered to be royal property, the Staufer on the other hand argued, that it belonged to the Salian heritage. The contentious assets had long been administered together with other Salian domestic estates, their origin was hard to determine and difficult to separate. Lothair advocated the principle that all of the assets in question had now become imperial properties due to the extinction of the Salian dynasty. The first armed engagements between Lothair and the Staufer took place as early as 1125 and increased in the years that followed. Lothair, with the approval obtained at a meeting of the princes in Regensburg, attempted to seize the crown lands, which provoked a Staufer reaction. Lothair then isolated Frederick II as he placed him under Imperial ban and withdrew the Franconian ducal fief from Conrad.