The Bronze Age in the Eastern Mediterranean region ended suddenly and violently about 1200 B.C. The Hittite Empire and the Mycenaean Greek Civilization were destroyed. Most of the cities in Syria and Palestine were destroyed. Egypt was attacked and permanently weakened. The region entered a dark age that lasted for centuries.
When I was first read about this, back in the 1960's, the most common explanation was that the catastrophe was caused by outside invaders, whose new iron weapons were superior to the bronze weapons of the Mediterraean civilization. This ended the Bronze Age and brought on the Iron Age.
Human action, though probably by small bands of raiders rather than mass invasions, is still the most plausible explanation for the disaster. Drews, in part two of The End of the Bronze Age, reviewed and eliminated the alternative theories.
However, the aggressors were not armed with iron weapons. They used bronze, just like the defenders. Checking the archaeological record, Drews presented the percentages of bronze and iron weapons:
Sandars, in The Sea Peoples also noted that iron weapons cannot be a critical factor in the disaster. In fact, some of the suspects, from Danube region in Central Europe, had access to excellent supplies of tin as well as copper, and knew how to use them. They had better bronze resources than the civilizations to the south.
The Iron Age did not really get going until long after the Bronze Age Civilizations fell.