My Nine Dragon Brides

Caden, a Golden Dragon, born with the Black Dragon, sealed the evil Black Dragon 5000 years ago. His power declined. To prepare for the Black Dragon breaking its seal, Caden helped nine individuals become emperors, establishing nine dynasties. He made a pact: the eldest daughter of the main lineage in each generation must not marry before thirty. They wait for him to form the Nine Phoenix Dragon Formation and kill the Black Dragon.