Sueki refers to blue-gray, hard-fired earthenware produced using firing techniques introduced from the Korean Peninsula around the middle of the Kofun period (early 5th century). Prior to this, Japan mainly had reddish, unglazed pottery such as Jomon pottery, Yayoi pottery, and Haji ware, all fired in open pit-firing methods.
The major difference between Sueki and earlier pottery lies in its firing technology. Although open firing (pit firing) can reach temperatures close to 1,000°C, because the fire is exposed, heat quickly escapes and the temperature is unstable. The use of kilns allowed for maintaining higher and more stable temperatures during firing.
Sueki rapidly spread throughout Japan and was widely produced. It likely served as important tableware for people at that time. The tradition of Sueki continued until the 15th century, with examples such as Suzu ware (Suzu-yaki). Sueki played a significant role in the development of Japanese pottery that continues to this day.