Einar Selvik is a Norwegian musician who leads the project Wardruna, which creates modern folk music using ancient Nordic spiritual concepts and instruments. Vikings composer Trevor Morris brought Selvik onboard to contribute to the soundtrack for the History series, which explores similar themes of Old Norse history and spirituality.

Selvik has even appeared on the show performing his compositions, which add authenticity and historical context to the series.

Selvik stopped by the TVGuide.com office to show off some of the instruments he uses for Vikings: the bukkehorn, the tagelharpa and the lyre.

The bukkehorn is a horn in both senses of the word — a musical instrument made from the horn of a goat — that creates a mournful sound perfect for funeral scenes. The tagelharpa is the oldest Scandinavian bowed instrument. It's a primitive, challenging instrument with three horsehair strings, but Selvik makes it sing. The lyre is a small harp that Selvik frequently uses for the score and has played on-screen.

Check out the video to see how all of them come together to create Vikings' haunting theme music.

<em>Vikings</em>Vikings

For more of Selvik's music, check out Wardruna on iTunes.

Vikings airs Wednesdays at 9/8c on History.