Personally, I feel that the usage of Late Roman is more appropriate for this name. This is because:• Graeco-Roman names like these became especially prevalent after the advent of Christianity, even though they were already around before that (as early as the 6th century BC, but I imagine they must gradually have become more commonplace after Greece came under Roman rule - first in 146 BC, definitively in 31 BC); • I cannot find evidence of Roman men named Diocletianus who lived in a century BC. The earliest I could find, is estimated to have lived in the 2nd century AD at the earliest and the 3rd century AD at the latest; • its most famous bearer, the Roman emperor, was born around 244 AD as Diocles (not Diocletianus) in what is now Croatia. This was after the start of the Crisis of the Third Century (c. 235–284 AD), which is generally seen as the starting point of Late Antiquity; • the hellenized form of this name is Διοκλητιανός (Diokletianos), which records show was only used in centuries AD (and not commonly, I might add).Also compare similar Graeco-Roman names, like Diogenianus and Menecratianus. For more information, please see:- https://en.wikipedia.org/wiki/Greece_in_the_Roman_era (in English) - https://en.wikipedia.org/wiki/Diocletian (in English) - https://en.wikipedia.org/wiki/Late_antiquity (in English) - Diokletianos at the Lexicon of Greek Personal Names (LGPN): http://clas-lgpn2.classics.ox.ac.uk/cgi-bin/lgpn_search.cgi?namenoaccents=%CE%94%CE%B9%CE%BF%CE%BA%CE%BB%CE%B7%CF%84%CE%B9%CE%B1%CE%BD%CE%BF%CF%82 (in English; features 7 results) - Caius Iulius Diocletianus (between 180 AD and 270 AD): https://edh-www.adw.uni-heidelberg.de/edh/inschrift/HD019328&lang=en (in English) - Licinius Diocletianus (between 254 AD and 268 AD): https://edh-www.adw.uni-heidelberg.de/edh/inschrift/HD033146&lang=en (in English)
• Graeco-Roman names like these became especially prevalent after the advent of Christianity, even though they were already around before that (as early as the 6th century BC, but I imagine they must gradually have become more commonplace after Greece came under Roman rule - first in 146 BC, definitively in 31 BC);
• I cannot find evidence of Roman men named Diocletianus who lived in a century BC. The earliest I could find, is estimated to have lived in the 2nd century AD at the earliest and the 3rd century AD at the latest;
• its most famous bearer, the Roman emperor, was born around 244 AD as Diocles (not Diocletianus) in what is now Croatia. This was after the start of the Crisis of the Third Century (c. 235–284 AD), which is generally seen as the starting point of Late Antiquity;
• the hellenized form of this name is Διοκλητιανός (Diokletianos), which records show was only used in centuries AD (and not commonly, I might add).
Also compare similar Graeco-Roman names, like Diogenianus and Menecratianus. For more information, please see:
- https://en.wikipedia.org/wiki/Greece_in_the_Roman_era (in English)
- https://en.wikipedia.org/wiki/Diocletian (in English)
- https://en.wikipedia.org/wiki/Late_antiquity (in English)
- Diokletianos at the Lexicon of Greek Personal Names (LGPN): http://clas-lgpn2.classics.ox.ac.uk/cgi-bin/lgpn_search.cgi?namenoaccents=%CE%94%CE%B9%CE%BF%CE%BA%CE%BB%CE%B7%CF%84%CE%B9%CE%B1%CE%BD%CE%BF%CF%82 (in English; features 7 results)
- Caius Iulius Diocletianus (between 180 AD and 270 AD): https://edh-www.adw.uni-heidelberg.de/edh/inschrift/HD019328&lang=en (in English)
- Licinius Diocletianus (between 254 AD and 268 AD): https://edh-www.adw.uni-heidelberg.de/edh/inschrift/HD033146&lang=en (in English)