I have heard that between 900 AD and the 1700's-1800's Europe was in a mini ice age. It probably could have started as early as mid 500 AD. I didn't pay much attention to the exact starting date...I was more surprised by the ending date being so close to our times.
Krakatoa erupted some time in there too. The whole world supposedly had no sun for about 3 days and there was snow in the summers due to the particles blocking out the heat of the sun, making the average earth temperature much cooler for a while.
I think you have three different incidents/times involved. All those did happen though.