his conquest in the Carpathian Basin. The Abodrites who lived in "Dacia on the Danube as neighbors of the Bulgars" sent envoys to Emperor Louis the Pious in 824, complaining "about vicious aggression by the Bulgars" and seeking the emperor's assistance against them, according to the Royal Frankish Annals. The Abodrites inhabited the lands along either the Timiș or the Tisza. According to a memorial inscription from Provadia, a Bulgar military commander, Onegavonais, drowned in the Tisza, implying Omurtag of Bulgaria's attempts to expand his rule in the region in the 820s. The Bulgars invaded Moravia in 863 and 883, suggesting that they controlled at least the crossing-points across the rivers Mureș and Tisza, according to the historian István Bóna. Bóna writes that the Bavarian Geographer is the last source which contains contemporaneous information of the eastern regions of the Carpathian Basin in the 9th century. According to this source, which is actually a list of the tribes inhabiting the lands east of the Carolingian Empire around 840, the Merehani, who had 30 civitates, or fortified centers, lived along the southernmost parts of the empire's eastern frontiers. Their land also bordered on Bulgaria. According to an alternative theory of the location of Moravia, which is primarily based on the Bavarian Geographer and Emperor Constantine Porphyrogenitus's report of "great Moravia, the unbaptized", Banat was the center of this early medieval polity, which was annihilated by the conquering Magyars. Archaeologist Silviu Oța identifies the Merehani with the Abodrites, adding that they were obviously a Slavic tribe. The name of the Karaš and other rivers implies that a population speaking a Turkic languageAvar, Bulgar, or Pechenegalso inhabited the Banat in the Early Middle Ages, but those rivers may have received their names only in the 11th and 12th centuries. Historian Vlad Georgescu writes that archaeological research has proven the existence of about 60 settlements in Glad's duchy. Other historians, including Sălăgean and Pop, say that the earth-and-wooden or stone fortresses unearthed at Bulci, Cenad, Ilidia, Orșova, Pescari, and Vladimirescu were Glad's forts. Florin Curta says that the dating of these sites is uncertain. Anonymus's narration Glad and his duchy According to the Gesta Hungarorum, Rus' princes gave a short description of the Carpathian Basin to the Magyar commanders before they decided to invade the territory. The princes told them that "Slavs, Bulgarians, Vlachs, and the shepherds of the Romans" inhabited the territory. In