In contemporary historiography and archaeology, the narratives of "De Administrando Imperio" have been reassessed as they contain anachronisms and factual mistakes. The account in "DAI" about the Serbs mentions that they requested from the Byzantine commander of present-day Belgrade to settle in the theme of Thessalonica, which was formed ca. 150 years after the reign of Heraclius which was in the 7th century. For the purposes of its narrative, the DAI formulates a mistaken etymology of the Serbian ethnonym which it derives from Latin "servi" (serfs).