A legend from the Goryeo era speaks of six states in the Gaya domains; however, other evidence suggests there were no less than ten small states in the region.
The "Six-Gayas Theory": A Reinterpretation
Historians of the Gaya kingdoms usually assume the existence of the so-called "six Gayas," which is taken to include Geumgwan-gaya and Ara-gaya. What, then, is meant by the notion that Gaya consisted of six small states and that the name of each small state was "'so-and-so' Gaya"?
The names of these six Gayas first appear in the five Gaya section in Samguk-yusa, a work produced during the last period of the Goryeo Dynasty. In this work, the names of seven Gayas are mentioned--Ara-gaya, Goryeong-gaya, Dae-gaya, Seongsan-gaya, So-gaya, Geumgwan-gaya, and Bihwa-gaya.
These names have been associated with the legend of six eggs, a birth myth of King Suro in Garak, a small ancient Korean state (42 A.D.-532 A.D.) described in Samguk-yusa. The expression"six Gayas" was coined simultaneously with such words as Hugoguryeo and Hubaekje in the years of confusion between the final period of Silla and the early days of Goryeo. As such, the names of the states ("'so-and-so' Gaya") do not refer to the time Gaya existed as small states, but to the time between the final days of Silla and the early Goryeo era. This indicates that the "six Gayas" existed earlier as members of the Gaya confederation, which included the states Geumgwan, Ara, Godongram, Seongsan, and Bihwa.
As the history of the confederation of Gaya in the early days of Goryeo is unclear, it is doubtful that the seven small states of Gaya listed in Samguk-yusa were actual members of the state confederation of Gaya at that particular time. Moreover, when we consider the wide area of dispersal in which Gaya pottery has been excavated, we can more realistically hypothesize that the number of small nations which originally composed the state confederation of Gaya was not six, but exceeded ten.