You searched for: “terrae incognitae
terra incognita (s) (noun), terrae incognitae (pl)
1. An unknown land; an unexplored region: Before people existed, the world had only terrae incognitae.
2. A new or unexplored field of knowledge: The expression terra incognita is often used in referring to matters about which one is uninformed, e.g. "I don't think I can do this because it is terra incognita to me."