The origin of the name ''Serbia'' is unclear. Historically, authors have mentioned the Serbs ( / Срби) and the Sorbs of Eastern Germany (Upper Sorbian: ''Serbja''; Lower Sorbian: ''Serby'') in a variety of ways: ''Cervetiis'' (''Servetiis''), ''gentis '', ''Suurbi'', ''Sorabi'', ''Soraborum'', ''Sorabos'', ''Surpe'', ''Sorabici'', ''Sorabiet'', ''Sarbin'', ''Swrbjn'', ''Servians'', ''Sorbi'', ''Sirbia, Sribia, Zirbia, Zribia'', ''Suurbelant'', ''Surbia'', ''Serbulia'' / ''Sorbulia'' among others. These authors used these names to refer to Serbs and Sorbs in areas where their historical and current presence is not disputable (notably in the Balkans and Lusatia). However, there are also sources that mention the same or similar names in other parts of the World (most notably in the Asiatic Sarmatia in the Caucasus).