Task: Question Generation
Input (English): Even though the Gelug exchanged gifts with and sent missions to the Ming court up until the 1430s, the Gelug was not mentioned in the Mingshi or the Mingshi Lu. On this, historian Li Tieh-tseng says of Tsongkhapa's refusal of Ming invitations to visit the Yongle Emperor's court:
Output (English): Until what year frame did the Gelug exchange gifts with the the Ming?