Civil wars. Probably the most important single cause of Byzantium's collapse was its recurrent debilitating civil wars. Three of the worst periods of civil war and internal infighting took place during Byzantium's decline.
The civilization of Ancient Greece emerged into the light of world history in the 8th century BC. Normally it is regarded as coming to an end when Greece fell to the Romans, in 146 BC. However, major Greek (or “Hellenistic”, as modern scholars call them) kingdoms lasted longer than this.
Hope this helps —- xoxo
