and Herzegovina (Zahumlje). Vlastimir married off his daughter to Krajina, the son of a local župan of Trebinje, Beloje, in 847–48. With this marriage, Vlastimir elevated Krajina to archon. The Belojević family was granted the rule of Travunija. Krajina had a son with Vlastimir's daughter, named Hvalimir, who would later on succeed as župan of Travunia. Vlastimir's elevation of Krajina and the practical independence of Travunija show, according to Živković, that Vlastimir was a Christian ruler who very well understood the monarchical ideology that developed in the early Middle Ages. Soon after 846, with the end of the thirty-year-truce, Malamir (or Presian) invaded the regions of the Struma and the Nestos, and Empress-Regent Theodora (r. 842–855, the wife of Theophilos) answered by attacking Thracian Bulgaria. A brief peace was concluded, then Malamir proceeded to invade Macedonia. The Bulgarians also imposed their rule on the Morava region, on the frontier between Serbia and the Bulgarian Khanate. The Byzantines were also active in the hinterland of Dalmatia, to the west of Serbia; the strategos of the cities of Dalmatia came into conflict with a Frankish vassal, the Croatian Duke Trpimir, in 846 or 848, in which the strategos was defeated. The defeat of the Bulgarians, who had become one of the greater powers in the 9th century, shows that Serbia was an organized state, fully capable of defending its borders, and possessing a very high military and administrative organizational structure. It is not known whether Serbia at the time of Vlastimir had a system of fortifications or a developed military organization with clearly defined roles for the župan. Prince Mutimir (ruled c. 851–891), the son of Vlastimir, managed to defeat the Bulgarians once again in 834–835, also capturing the son of the Bulgar Khan. The Serbs and Bulgarians made peace. The remaining years were marked by internal dynastic wars. In 892, prince Pribislav Mutimirović was overthrown by his cousin, prince Petar Gojniković. By the middle of the 9th century, the process of Christianization of Serbia was finalized, and the Eparchy of Ras was established, in the time of Byzantine emperor Basil I. Petar, Pavle, Zaharija and Časlav Prince Petar Gojniković was recognized by the Bulgarians, now the greatest power in Southeastern Europe, although the peace was not to last; the Byzantines had sent an envoy to Serbia promising greater independence in return for Petar leading an army against the Bulgarians. A Bulgarian