primaeval
adjective /praɪˈmiːvl/
  /praɪˈmiːvl/
 (British English) (also primeval British and North American English)
 [usually before noun]- from the earliest period of the history of the world, very ancientTopics Historyc2
 - (formal) (of a feeling, or a desire) very strong and not based on reason, as if from the earliest period of human life