Kaleo is a indie folk alternative singer?
Is that his genre? I guess he was popular in the sense that his music peaked at #1 on Billboard's charts. Maybe folk-pop is a better label.
You enjoy nordic style music though? He's got a lot of info out there.
Maybe "rock/folk-pop musicians from the nordics" is a better way to put it. For example, I'm also a fan of Of Monsters And Men, and they're from Iceland.
I think I remember something about there being vikings in onf of thier things.
There must've been. If you watch their music videos, they certainly incorporate a substantial amount of nordic folklore into them.
What other bands do you like of them? 
ABBA (a classic!) and Swedish House Mafia are pretty good. Swedish House Mafia's music is of the progressive house genre though, which I also enjoy.
O, Swedish was going to Croatia! They are popular. 
Ah, I guess I'll need to check them out! Got any other recommendations? I'd be into lesser-known groups as well.