In the decades before 1177 BC, there were eight empires on the Mediterranean. After, there were three barely-surviving city-states. That the "sea people" came into the picture just as things collapsed is not a coincidence. They were largely the desperate displaced people from fallen civilizations, both victims and agents of violence, acting in a feedback loop. It took centuries to recover; there's a reason it's called the Greek Dark Ages.
I also have a strong feeling that this collapse and the roving sea peoples are what the Illiad narrates. Or at least the body of traditional oral lyric poetry it's inspired on.
