Bosnia is first mentioned ''as a land (horion Bosona)'' in Byzantine Emperor Constantine Porphyrogenitus' ''De Administrando Imperio'' in the mid 10th century, at the end of a chapter (Chap. 32) entitled ''Of the Serbs and the country in which they now dwell''. This has been scholarly interpreted in several ways and used especially by the Serb national ideologists to prove Bosnia as originally a "Serb" land. Other scholars have asserted the inclusion of Bosnia into Chapter 32 to merely be the result of Serbian Grand Duke Časlav's temporary rule over Bosnia at the time, while also pointing out Porphyrogenitus does not say anywhere explicitly that Bosnia is a "Serb land". In fact, the very translation of the critical sentence where the word ''Bosona'' (Bosnia) appears is subject to varying interpretation. In time, Bosnia formed a unit under its own ruler, who called himself Bosnian. Bosnia, along with other territories, became part of Duklja in the 11th century, although it retained its own nobility and institutions.