The correct answer is antebellum.
The Antebellum period in America history is generally considered to be the period before the Civil War. The southern United States at that time is often called 'the antebellum South'.
The term antebellum refers to any given time before a war. It comes from the Latin phrase ante bellum which means literally 'before the war'.
The synonym of antebellum is nonmodern, or of characteristics of an earlier time.
