noun which may take the genitive case particle 'no'
prehistoric
Refers to the period before written records; used attributively with の.
この地域では歴史以前の遺跡が発見された。
Prehistoric ruins were discovered in this area.
Also means 'prehistoric', but is more technical and often used in academic contexts like 先史時代 (prehistoric era). 歴史以前 is a more descriptive, everyday term.
Compound of 歴史 (history) and 以前 (before, previous). The reading is the standard on'yomi combination.