Initially, the Arab Muslims in Eastern and Central Europe took white slaves to sell them to Arabia," Senegalese author Tidiane N'Diaye told DW in an interview. "But the growing military power of Europe put an end to Islamic expansion and now that there was a shortage of slaves, Arab Muslims were looking massively to black Africa."
Explanation: the Roman Empire was long-lived for many reasons, some of which being new laws and engineering, military potency, and social legislation to combat political fragmentation along with exceptional leaders.
Greeks (Hellenic) were isolated and their civilization was termed classic because it was not heavily influenced by outside forces. Hellenistic (Greek-like) refers to Greeks and others who lived during the period after Alexander's conquests.