Based upon the difference in the word "hundred" in Latin (centum) and Asvestan (satem) two language families have been identified. The western, centum, family includes Greek, Latin (with the Italic dialects), Venetic, Germanic, Celtic, Hittite and Tocharian although this latter does not occur in the West. The "satem" languages are Slavic, Baltic, Albanian, Armenian and Aryan. This difference cannot be explained by developments within the individual languages, it must therefore have existed in the Indo-European.