The Era of Solitude was the period in time in the history of the Sleestak.
The Era of Solitude came after the Era of Intelligence, and the Purge of the Lost City. It was the period in time when there was only darkness. The Altrusians became less intelligent as they had nothing to look at except hard rock and each other. During this time the Sleestak eventually became ruled by a Sleestak called, Sol. Sol reorganized the Sleestak and taught them how to hunt and kill.