This forced the Anglos and Saxons into the Denmark area. Some say they went to Britannia because of Huns moving into Denmark. I don't know how much evidence there is to support that second move. Some say the Huns' initial migration west/southwest was because of climate change -- getting too cold. Life sucks when crop yields lower, rain patters become less predictable, and deaths from plague increase.
All of these events occurred during the cooling period called the Dark Age. In the graph below, find the top of the red hump titled Roman Warm Period, which topped out around AD 300 in most studies. And follow it to the right to the bottoming of the blue dip (most studies that's around AD 900). That's roughly 600 years of cooling. The more we all learn about how bad life was during the recent two cooling periods (Dark Age, followed by Little Ice Age), the more we'd all laugh at the left every time they tell us to hate life in the Modern Warm Period.

I didn't see anything in the article identifying the Y-DNA of the males they found. The Q haplogroup is extremely rare in Europe but is found in Siberia (and is very common in the New World)--I have wondered if it was brought to Europe by the Huns. (It's not my haplogroup but is found in a couple of families I am descended from.)