I've seen some maps that shows the hun empire controling modern day Denmark, and even parts of Sweden. I couldn't find any information on this, is there any evidence of that being the case?
Tl;dr: Disputed at least for about half a century long among Scandinavian scholars - While the majority of scholars does not accept the possibility of Attila's exerting any real influence in Scandinavia, a few scholars (especially Danish Archaeologist Lotte Hedeager) suppose that their influence can be attested both in the 5th century written and archaeological (artifacts') evidence.
The key text on this topic is a passage in Fragment 8, the most important contemporary account of Priscus of Panion who was a member of the diplomatic envoys of Eastern Roman Empire (and cited in later texts).
Priscus witnesses and narrates the meeting between Attila and some other envoys while he was staying in the court of Attila, and one of them from Italy (Western Roman Empire), called Romulus, uses flattery to Attila as following:
"'No ruler in Scythia', he [Ambassador Romulus of WRE] said, 'or in any other land ever accomplished so many things in such a short time: ruling the islands in the Ocean [bold by me, /u/y_sengaku] and requiring even Romans, let alone all the Scythia, to pay tribute' (Given trans. 2014: 68)."
So, the scholarly debate above mainly concern the identification of these "islands in the Ocean" as well as the validity of the ambassador's flattery in reality. Hedeager also mentions the presence of a new, allegedly distinct style of metal (especially gold) from the 5th century in northern Europe (around the Baltic) as a trace of the direct contact between the Huns and groups of peoples there, but this archaeological evidence is also disputed.
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