Avant-garde styled, obscure Death Metal from Notodden created during 1991 featuring EMPEROR personnel Samoth (a.k.a. Tomas Thormodsæter Haugen), Ihsahn (Vegard Sverre Tveitan) and Ildjarn (Vidar Vaaer). The band went through a slew of formative titles before settling on THOU SHALT SUFFER. Initially founded in Akkerhaugen as DARK DEVICE then XERASIA, the formative trio comprised vocalist / bassist Finn Arne Nielsen, guitarist Tomas Thormodsæther Haugen with Ronny Johnson on drums. A 1990 live rehearsal demo was issued under the XERASIA banner prior to a name change EMBRYONIC, having replaced Nielsen with Vegard Sverre Tveitan and releasing the demo 'The Land Of Lost Souls', recorded in November 1990 at Notodden Lydstudio. Subsequently the act morphed again into THOU SHALT SUFFER.

THOU SHALT SUFFER was created by Ihsahn and Samoth in parallel to EMPEROR's formation. Session drums would be supplied by Thorbjørn Akkerhaugen, proprietor of Akkerhaugen Lydstudios. First product was a 1991 7" single released through Distorted Harmony entitled 'Open Mysteries Of Your Creations', limited to 1100 copies. Also emerging that year would be a rehearsal demo and the 'Into The Woods Of Belial' set.

Subsequently, Ihsahn continued the venture as a solo undertaking, delving into more ambient landscapes. Although THOU SHALT SUFFER remained a background force to his main activities, with the archive demo sessions 'Into The Woods Of Belial' surfacing in 1997 on Samoth's own Nocturnal Art Productions, the Candlelight label collected together archive demos for a 2001 release 'Somnium'.

Ihsahn has a wealth of extreme Metal affiliations besides THOU SHALT SUFFER and EMPEROR including ARCTURUS, ILDJARN, PECCATUM, ULVER, STAR OF ASH and WONGRAVEN. An IHSAHN solo album, ' 'The Adversary', saw release in April 2006.