Drummer Jaakko and former guitarist Asko Sartanen formed Imperanon in autumn 1999. Soon after Aleksi Sihvonen and Eki Nurmikari joined Imperanon, and band recorded their first demo "Until The End" in 2002. Imperanon proved already then to have a good grasp for sparkling melodies mixed with powerful riffs and rough, haunting vocals. During the fall of 2002 musical differences between Asko and the rest of the band climaxed to the separation of Asko from the group.

To Imperanon´s fortune, Aleksi Virta was found to play keyboards and with him came Lauri Koskenniemi, at least as good with the 6 string as Virta with his keys. The next demo, "Imperanon", was completed in 2003 and left quite a mark amongst metal journalists and fans. Raving reviews and first gigs in several Finnish clubs substantiated the young band's amazing skills. And not surprisingly, "Imperanon" went out of stock very soon.

Eventually, Imperanon's new songs led to a recording contract from the leading independent metal label Nuclear Blast.

During December 2003 and January 2004, Imperanon entered the Sonic Pump Studios in Helsinki together with Nino and Titus from Thunderstone to start working on full-length debut album "Stained".

After debut album Lauri Koskenniemi resigned from Imperanon. In summer 2004 Teemu Mäntysaari joined Imperanon.

In spite of their youth, Imperanon demonstrate that it's not a question of age to create mature and diverse songs.

In 2005, the band recorded a three song demo. However, this demo was never released to the public, and is not included on discographies. In 2006, Imperanon released a yet another demo, known only as 2006 Demo and having no cover art. On July 20th, 2007, the band issued a statement via MySpace announcing that they had broken up and gone their separate ways, most likely due to Teemu Mäntysaari's dedication to Wintersun and Aleksi Sihvonen's joining of the Finnish Death/Thrash band Medicated.