Gunpowder first came to Korea in the mid 1300s, but it was not until the 1370s when Korea began its own production. Choe Mu-seon copied various Chinese gunpowder weapons including cannons and rockets. During the reign of Taejong of Joseon, improvements were made, and still more were made by Sejong of Joseon in the 1440s. During the mid 16th century the classic "Cheonja", "Jija", "Hyeonja", and "Hwangja" chongtong appeared. Earlier in the century, the bullanggi, a breech-loading swivel gun was introduced from Portugal via China.