According to the "De Administrando Imperio" (DAI), the Serbs settled the Balkans under the protection of Byzantine Emperor Heraclius (r. 610–41), and were ruled by a dynasty known in historiography as the Vlastimirović dynasty. Slavs had begun settling the region in the early 6th century, after raiding deep into the Empire. They settled "baptized Serbia" (the "Serbian hinterland", anachronistically known as "Raška"), which included Bosnia, and the maritime lands ("Pomorje") of Travunija, Zahumlje and Paganija, while maritime Duklja was held by the Byzantines, it was presumably settled with Serbs as well. All of the maritime lands bordered "baptized Serbia" to the north. In the mid-9th century, the hitherto peaceful neighbour of Bulgaria invaded but was defeated in war. Serbia was Christianized in ca. 870, although missions had been made during Heraclius' reign. In the following decades, members of the dynasty fought succession wars, and Serbia became a matter of Byzantine-Bulgarian rivalry. The written information regarding the dynasty ends with the DAI and Prince Časlav's death (ca. 950), after which the realm crumbled into pieces. The Byzantines established a short-lived catepanate at Ras, with military governorship ending soon thereafter with the Byzantine conquest of Bulgaria, and was re-established only ca. 1018 with the short-lived Theme of Sirmium, which however did not extend much into Raška.