Why was it the case that Troy, Mycean, and the Hittite Empire fell one after the other?

The political-economic system that consists of the Mycenae on the West, Troy/Wilusa in Northeast Anatolia, Hittite in Central-Anatolia, and Mittani, Egypt and the states in Lower Mesopotamia disintegrated around 1200s B.C. E. It is considered that this disintegration began with the appearance of the "Sea Peoples" in the East Mediterranean region; however, there are various unanswered questions related to this issue. On the other hand, while all this is happening in the East, Mycenaean Central Palaces are burned down.

All the other powers in West Anatolia, including Troy, are completely destroyed. The Great Hittite Empire is completely destroyed due to internal political conflicts; even though Egypt does not fall under Ramses III, it becomes considerably weaker. Consequently, the "world order" that lasted for centuries was destroyed. In this destruction, it is certain that wars, political conflicts, attacks from outside, and natural disasters all played important roles. It is going to take a long time (around four hundred years) for the subsequent "Dark Ages" to end.