This looks like the full Roman empire before its decline in the post classical era. A defining point indicating a time frame is at the topmost left in Britannia. Roman Emperor, Hadrian, had a wall built-you can just barely see the straight line at the tip of the empire. Construction began in 122 CE, and remained patrolled for another 250 years, at which time the empire began to crumble.
”There were 46 provinces under Trajan, a figure that would grow to 96 by the reign of Diocletian (285-305). In Trajan's time, provinces in the interior of the country were run by governors chosen by the Senate, a legislative body run by leading aristocrats. In contrast, border provinces were run by governors named directly by the emperor.”
The barbarian tribes who carved up the old empire — the Franks, Visigoths, Ostrogoths, the Vandals, and so forth — were much more Romanized than the tribes that had menaced Rome centuries earlier. The rulers of these new kingdoms generally sought to co-opt Roman elites that still held significant wealth and power across the former Western Empire.