That game was not the prequel for Barbarian II, not at least in my ZX Spectrum and I think not in the rest of systems.
There were TWO Barbarians. Barbarian by Palace Software (see it in
http://en.wikipedia.org/wiki/Barbari...mputer_game%29 , it was the TRUE prequel to Barbarian II) and Barbarian by Psygnosis (wikipedia:
http://en.wikipedia.org/wiki/Barbarian_%28Psygnosis%29 ), a totally unrelated game.
I think Barbarian by Psygnosis came out for sale at rougly the same time Barbarian II by Palace Software, but I can not be so sure.