WINTERSUN was founded as the solo project of Jari Mäenpää (a.k.a. 'Arbaal'), a man holding credits with IMMEMORIAL, ENSIFERUM, CADACROSS and ARTHEMESIA. Session drums came courtesy of Kai Hahto (a.k.a. Generis), of CARTILEGE, ROTTEN SOUND, AGRESSOR, VOMITURITION, WINGS and ENOCHIAN CRESCENT repute.

Upon his signature to Nuclear Blast Records in 2003, in preparation for a debut album arriving in September the following year, Mäenpää relinquished ties to former acts. Shortly after release of the 'Wintersun' album in September 2004 WINTERSUN parted ways with guitarist Oliver Fokin, replacing him in December with Teemu Mäntysaari of IMPERANON. Jari Mäenpää, retaining his role in ARTHEMESIA, exited ENSIFERUM during 2005 in order to prioritise WINTERSUN.

The project commenced recording of a second album, 'Time', in May 2006 at Sonic Pump Studios with Nino Laurenne. WINTERSUN teamed up with AMON AMARTH and TYR for a European tour, covering Germany, Italy, the Czech Republic, Hungary, Poland, France, the UK, Holland, Belgium, Sweden and Norway, beginning in early November.

On February 16th 2007 Kai Hahto was honoured with the "Musician of the Year" award at the Finnish Metal Awards, which were held during the Finnish Metal Expo at the Cable Factory in Helsinki, Finland. 'Time' was finally mixed in May 2007 for August release.