The hypothesis that Dacian was widely spoken to the north-west of Dacia is primarily based on the career of Dacian king Burebista, who ruled approximately between 80 and 44 BC. According to Strabo, Burebista coalesced the Geto-Dacian tribes under his leadership and conducted military operations as far as Pannonia and Thracia. Although Strabo appears to portray these campaigns as short-term raids for plunder and to punish his enemies, several Romanian scholars have argued, on the basis of controversial interpretation of archaeological data, that they resulted in longer-term Dacian occupation and settlement of large territories beyond the dava zone.