Faced with an empty treasury, he discontinued Justinian's practice of buying off potential enemies. Immediately after his accession, Justin halted the payment of subsidies to the Avars, ending a truce that had existed since 558. After the Avars and the neighbouring tribe of the Lombards had combined to destroy the Gepids, from whom Justin had obtained the Danube fortress of Sirmium, Avar pressure caused the Lombards to migrate West, and in 568 they invaded Italy under their king Alboin. They quickly overran the Po valley, and within a few years they had made themselves masters of nearly the entire country. The Avars themselves crossed the Danube in 573 or 574, when the Empire's attention was distracted by troubles on the Persian frontier. They were only placated by the payment of a subsidy of 60,000 silver pieces by Justin's successor Tiberius.