[SunkenCiv]

https://www.nytimes.com/2002/03/26/science/tree-rings-show-a-period-of-widespread-warming-in-medieval-age.html

[SunkenCiv]

[snip] The Avars were a confederation of heterogeneous (diverse or varied) people consisting of Rouran, Hephthalites, and Turkic-Oghuric races who migrated to the region of the Pontic Grass Steppe (an area corresponding to modern-day Ukraine, Russia, Kazakhstan) from Central Asia after the fall of the Asiatic Rouran Empire... [/snip]

https://www.ancient.eu/Avars/

http://www.google.com/search?q=migration+of+the+avars