It shared many similarities in its art, such as crowns with tree-like protrusions which are seen in Baekje and Silla. Many of the artifacts unearthed in Gaya tumuli are artifacts related to horses, such as stirrups, saddles, and horse armor. Ironware was best plentiful in this period than any age. North-South States North South States Period (698–926 CE) refers to the period in Korean history when Silla and Balhae coexisted in the southern and northern part of Korea, respectively. Unified Silla Unified Silla (668–935) was a time of great artistic output in Korea, especially in Buddhist art. Examples include the Seokguram grotto and the Bulguksa temple. Two pagodas on the ground, the Seokgatap and Dabotap are also unique examples of Silla masonry and artistry. Craftsmen also created massive temple bells, reliquaries, and statutes. The capital city of Unified Silla was nicknamed the "city of gold" because of use of gold in many objects of art. Balhae The composite nature of the northern Korean Kingdom of Balhae (698–926) art can be found in the two tombs of Balhae Princesses. Shown are some aristocrats, warriors, and musicians and maids of the Balhae people, who are depicted in the mural painting in the Tomb of Princess Jeonghyo, a daughter of King Mun (737-793), the third monarch of the kingdom. The murals displayed the image of the Balhae people in its completeness. The remains of ten Buddhist temples have been found in the remains of the capital of Balhae, Sanggyeong, together with such Buddhist artifacts as Buddha statuettes and stone lanterns, which suggests that Buddhism played a predominant role in the life of the Balhae people. The Balhae tomb Majeokdal in Sinpo, South Hamgyong Province, are associated with pagodas and temples: This also indicates that Buddhism had a strong influence over the funerary rituals in Balhae. Goryeo dynasty The Goryeo dynasty lasted from 918 CE to 1392. The most famous art produced by Goryeo artisans was Korean celadon pottery which was produced from circa 1050 CE to 1250 CE. While celadon originated in China, Korean potters created their own unique style of pottery that was so valued that the Chinese considered it "first under heaven" and one of the "twelve best things in the world." Jinsa "underglaze red", a technique using copper oxide pigment to create copper-red designs, was developed in Korea during the 12th century, and later inspired the "underglaze red" ceramics of