Another big volcanic event about 536 AD changed Europe.
Historical sources describing a fog covering the sun combined with reduced growth seen in tree rings suggest that erupting volcanoes caused a dramatic cooling in Europe after the year 536, coinciding with a time of general crisis and local catastrophes with estimated 25 to 50 million of victims. Some historians even argue that the cool climate accelerated the collapse of the Roman Empire, leading Europe into chaotic times, with widespread migrations of peoples within or into Europe fleeing famine, diseases and war.
Good article. Thanks.