The Five Centuries Regency was a period of time between the First Dynasty and the Second Dynasty in which for 489 years the New Shi'ar Imperium was governed without an Imperial Sovereign.  No less than 66 members of the Imperial Council were selected by random lottery to serve as Imperial Regent.  No Regent served in that positon for more than 10 years. 

This portion of the Early New Shi'ar Imperial Era also saw the Imperium plagued by several civil wars as dissident Shi'ar supported claimants to the throne on Chandilar