 In c . 1250 BC , the first wave of destruction has been witnessed in various centers of mainland Greece for reasons that cannot be identified by archaeologists . In Boeotia , Thebes was burned to the ground , around that year or slightly later . Nearby Orchomenos shared the same fate , while the Boeotian fortifications of Gla were deserted . In the Peloponnese , a number of buildings surrounding the citadel of Mycenae were attacked and burned . 
