The theory of 6 Gaya originated in the early Goryeo Period. In actuality, there were more than 10 small Gaya Kingdoms. In general, when the history of Gaya is mentioned, people think of the names of 6 Gaya Kingdoms. Then, why was each kingdom called so and so Gaya? The first record of 6 Gaya Kingdoms can be found in the record of "5 Gaya Dynasties" in Samgukyusa(the legend and history of Three Kingdoms written by Ilyeon in the Goryeo Peropd). In the record, 7 Gaya Kingdoms including Ara Gaya, Goryeong Gaya, Dae Gaya, Seongsan Gaya, So Gaya, Geumgwan Gaya, and Bihwa Gaya were mentioned. These names were added to the legend of 6 eggs attached to the King Suro of Garak Kingdom. The concept of 6 Gaya Kingdoms was formed between the late Silla Period and early Goryeo Period. Therefore, the names of Gaya Kingdoms were not actually used at the time of their existence. But they were named later to indicate the Gaya confederation including Geumgwan Kingdom, Ara Kingdom, Godongnam Kingdom, Seongsan Kingdom and Bihwa Kingdom.
It is not clear whether the 7 Gaya Kingdoms recorded in Samgukyusa were actually members of Gaya confederation. In addition, excavations of Gaya earthenware indicate that there were more than 10 Gaya Kingdoms. Therefore, it is time to overcome the theory of 6 Gaya Kingdoms and restructure the history of Gaya based on "Wiseo, Dongijeon" of Sanguo Zhi(History of Three Kingdoms(Wei, Shu, and Wu of China) compiled by Chen Shou. In the Dongijeon, histories of Korea and other nations in the east are recorded), Samguksaki(History of Three Kingdoms written by Kim Busik in the Goryeo Period), and Nihonshoki(History of Japan compiled in the Nara Period).(By Kim Tae-sik)