Original sentence: Longquan celadon was first produced in Longquan, around 900 AD, and the manufacture of celadon ware spread to Korea some 100 years later, where this style of art was further refined
Edited sentence: Longquan celadon was first produced in Longquan, around 900 AD, and the manufacture of celadon ware spread to Korea some 100 years later who started to perfect this style of art