This research figured out the relationship between tombs that were revealed with its large burial mound tombs through excavating investigation in Gaya region and ancient mountain fortress that were built in the surrounding area.
It can be assumed that the tombs and its large burial mound tombs had been the political and cultural center zone of each small country of Gaya. And while most of the construction of large burial mound tombs stop from mid 6th century with the exception of Ok-jeon tombs in Hapcheon, the construction of mountain fortress expands to west region of Gyeongnam province and southern coast region with the beginning of construction in Changnyeong and Haman region in mid 6th century.
The mountain fortresses which were constructed in the progress of advance of Shilla, can be divided into two different form based upon their location. One is located in the hinterland or surrounding area of each different region’s central tombs, while the other one is located in the southern coast of Korea and the border zone of Baekje and Shilla. The former one is assumed that it had acted as a governing fortress to prevent the expanding power of Shilla and when considering the consecration of Choohwa mountain fortress, Milyang is assumed to had been a newly magnified city that Shilla had considered. On the other hand, the latter one is assumed that it had been constructed in the military purpose to be prepared with Baekje’s attack by Shilla which were trying to advance to such region. And the seaside fortresses of Geoje and Namhae region, such as Dundeokgi mountain fortress, Daeguk mountain fortress and etc are assumed that it had been regarded as important places for the purpose of defending Japanese raiders and sea trade.
In addition, before the advance of Shilla to Gaya region which turned out in the form of building mountain fortress, it is assumed that they first conducted a cultural advance, such as trade. And this assumption could be verified through the Shilla style remains that are found in the main tombs of Gaya. On the other hand, in case of tombs in Changnyeong, it turns out that its burial mound tombs was built from late 6th century to 7th century. So we can assume that clay strip culture still continued after the construction of mountain fortress by Shilla.