The Cheonja Chongtong gun is named after the Chinese character “cheon” (天) inscribed on its body. “天” is the first character of Qianziwen (Thousand Character Classic), and indicates that this gun was the first one of its kind produced in the Joseon Period. According to the inscription on the barrel, it was produced in 1555 (the 10th year of King Myeongjong’s reign). It is regarded as an important cultural heritage as it is the largest gun made during the Joseon Period and the oldest one containing a legible inscription.