After 867, when Basil I the Macedonian became Byzantine emperor, the Arabs in the southern Italy attacked the Dalmatian cities, including Dubrovnik. The citizens asked for Byzantine help so the emperor sent the ships headed by Niketas Ooryphas, the "Droungarios of the Fleet". He forced the Arabs into retreat and made them quit the blockade, thus reinstating the Byzantine maritime control in the Adriatic after several decades. This allowed for the Byzantines to use the local inhabitants from the Croatian and Serbian lands as the auxiliary naval detachments in the ensuing Byzantine-Frankish siege of the Arabic Bari in 870–871. It was recorded that various Slavic people participated on ships dispatched by the Ragusans: Croats, Serbs, Zahumlians, Travunians, Kanalites. The Byzantines ravaged the Adriatic coast then, setting administrative and political relations in the region, ordering for the towns and islands of Split, Trogir, Zadar, Cres, Rab and Krk to pay tribute to the Croatian state, and to Ragusa to pay tribute to the Serbian states of Zachlumia and Travunija.