This theme is the piece that plays during the title sequence of TV series "Game of Thrones", and was composed by Ramin Djawadi in 2011.

Some interesting facts from Wikipedia:

Ramin Djawadi began composing the music for the show after he had watched the first two episodes of the series that the showrunners David Benioff and D. B. Weiss sent him, and discussed the concepts of the show with them.
Djawadi was shown a preliminary animated Game of Thrones title sequence the visual effect artists were still working on, he was inspired to write the piece. He said that he started humming what would become the theme tune in the car after seeing the visuals for the title sequence, and conceived of the idea for the theme on the drive back to his studio.


This transcription is less simpler than previous ones, but still suitable for medium grade players: