Synonyms for Barbarous (same or very similar meaning)
WordNet sense 1 ((of persons or their actions) able or disposed to inflict pain or suffering):
brutal, cruel, fell, roughshod, savage, vicious
WordNet sense 2 (lacking and reflecting lack of pity or compassion):
inhumane
WordNet sense 3 (not having a high state of culture and social development):
noncivilised, noncivilized
From the ODE community, based on WordNet
add/edit