Current archives and Royan tales speak of the Exostrider, who descended through the Stridergate buried deep within Lahai-Roi. Down along its trail came Threnodian Aleph-1, and the two clashed in a fierce battle. At last, the Exostrider sealed Aleph-1 within the Stridergate itself. The Exostrider then drove its greatsword into the earth to hold up Lahai-Roi and the Roya Frostlands above.
Current research suggests the Exostriders and Sentinels were created with technology from the same civilization.
