Unlike Ryukyu or Vietnam, which both had a ‘Tributary/Appointment’ relationship with the Chinese Ming dynasty, and only requested and/or received posthumous titles for their Kings and no other, the Joseon dynasty received titles from Ming not only for the Kings but Crown princes as well. Ever since Joseon received titles for the King and the Crown prince from the Ming Emperor during King Taejong’s reign, the Joseon government continued to request such titles amidst problematic reign transfers, to which Ming also complied.
This particular practice of even the Joseon Crown princes receiving titles from Ming served as a certain cause of request (made to Ming) during King Seongjong’s reign, when the King’s biological parents former Crown prince Euigyeong and princess Subin Han were under consideration for receiving posthumous titles, which necessitated a request for Ming’s bestowal of such titles. The Joseon government argued that King Seongjong’s birth-father was a former Crown prince who had already received a title from Ming, and therefore already been acknowledged as a potential heir-apparent for the throne. Logically, there was a legitimate cause behind Joseon’s request.
At the time, the Ming government too had been issuing (since the Jeongtong era) posthumous titles for Crown princes and princesses of king-level families inside the Imperial family, who died before inheriting the kingship. Utilizing the situation, Madame Han, who as a wife of a meritorious Joseon vassal was serving the Ming court, and Ming eunuchs who were originally from Joseon, all entities with their own interests or stakes entangled in the matter, joined the lobby and contributed to Joseon’s request being
eventually granted by the Ming court.
There were many Emperors and Kings in either Ryukyu or Vietnam who had posthumous titles, but unlike Joseon, examples of either countries requesting them or receiving them from Ming is hard to find. The Joseon-Ming relationship was rather unique in that regard, and deserves more attention.