It's Era (Part 4) by Krasheninnikoff. It is
apparently copyright free, but the artist has become inactive and the music is missing from
the site they gave it away on. There is a Jon Krasheninnikoff Skarin with a song
Era which I have found listed as "Part 1." I can't find mention of any other parts or licensing information. I'm not sure if it's the same person. There are listings on Last.fm, but the tracks are unavailable.
My guess is Jon Krasheninnikoff Skarin is the same Krasheninnikoff, and he has removed his early work because it doesn't meet his current standards for himself. You could
contact him or just use it. Once copyright free = always copyright free doesn't it?