prehistoric

Having lasted from a remote period; having been of long duration; of great age, very old.

"an ancient city  an ancient forest"

Existent or occurring in time long past, usually in remote ages; belonging to or associated with antiquity; old, as opposed to modern.

"an ancient author  an ancient empire"

(history) Relating to antiquity as a primarily European historical period; the time before the Middle Ages.

(properly) Of or relating to the epoch before written record.