Can someone please tell me what culture this is from...?

It's Norse, Vikings. It depicts the world tree, Yggdrasil, which supports the nine worlds of Norse mythology. Seriously, just watch Thor. Look, you can see the eagle at the top of the tree, and the squirrel running up and down the trunk relaying messages to the eagle, and I think that lizard-looking thing at the base is Nidhogg. Just wiki it.