The conception of Sinsaenum can be traced as far back as 1998, when French guitarist Frédéric Leclercq (best known as the bassist of English power metal band DragonForce) began writing a number of death metal songs. After recruiting fellow French guitarist Stéphane Buriez of Loudblast for the project, Leclercq was contacted by American drummer Joey Jordison (known for his work with Slipknot, then a member of Scar the Martyr and later of VIMIC) with the intention of working together, who later became involved in the project.Jordison proposed the band name Sinsaenum, which is a modified portmanteau of the words "sin" and "insane". The trio later added Attila Csihar of Norwegian black metal band Mayhem and Sean Zatorsky of American death metal group Dååth as dual lead vocalists, in addition to Seth guitarist Heimoth on the bass to complete the lineup. The formation of the band was officially announced on May 20, 2016.