The origin of the Dan designation stems back from the Silver Intervention, when the silver dragons subjugated the divided clans into one nation, with a member of clan Dan placed at the head.
Ever since, any ruling individual of the nation of Danasia has been given the title of Dan. In early Danasia, it was customary for the heir to be of the source clan Dan, but as generations passed, the role was given to the individual who possessed the strongest ability to rule, most often exhibited through a trial of single combat.
In this way, Durtom Crûsgar, through defeating The Dan of that era, took control of the Danasian nation and established the ruling dynasty of Dankills. It was in this time that the capital was moved from Oldan to Gangdan.
The next Dan to be of the Danasian (and fittingly of the clan Dan) bloodline was Jodando Legault, who came from the western continent to reclaim the Danasian throne from the Dankills.