Santorini detonating turned the eastern Med into the bronze age equivalent of ‘Mad Max’.
Or it was the straw that broke the camel's back. Remember oil ran out in the Mad Max world leading to a nuclear exchange.
In the first Mad Max movie they are trying to keep the world together - it kind of still functions in the same way as the good old days but more debased, By the Road Warrior sequel the nukes already were detonated and it is the aftermath.
The volcanic explosion that blew most of Santorini (Thera) into the atmosphere happened several centuries before the collapse of the Bronze Age civilizations.