Hwaseong Dang Castle(唐城) is referred as Danghang Castle around which a lot of remains and relics belonged to the Era from Shilla Kingdom to North-South States Period were found, including sites for buildings and temples, pits, etc. It is assumed that there were massive clustered settlements that took an important role as a port city in the Era of Three Kingdoms to North-South States Period. Various kinds of roof tiles with inscription were excavated in the Dang Castle including the roof tiles on which Dang (‘唐’, meaning Tang Dynasty in Chinese) was inscribed. From the relics, it revealed that Dang Castle served as a governmental organization equipped with the residential facility, and warehouses to store goods. In the Sangan-ri Relic I and II were found building remains, residential sites, storage pits, the road remains, porcelain kilns, etc. There also were found a seal made of lead and stone on which codes were inscribed. From the remains, the Castle was assumed to have been a place where the government officials related to trade managed. Chinese wares excavated in Dang Castle showed the relation of trade with Tang Dynasty in China. It indicated the transport route at that time. Through the traffic route called Yeomjitong (meaning salt and water passage), we could assume the storage and transport of salt produced in the area of Namyang Bay and officials who managed the salt and warehouses for storage. Among the trade goods, there were goods from Southeast Asia and Western regions, indicating the regions worked as a place of international trade. There found roof tiles on which Baeksa (白寺 meaning Baek Temple) was inscribed in baekgok-ri relics and the temple site. Other relics were found as well including the head part of a Buddha statue, Y-shaped bowls of Shilla Kingdom, flower pattern-inscribed ware, roof tiles, etc. Renowned monks in the Shilla Kingdom had been to Tang Dynasty for their academic purpose through Dang Castle. It was assumed that the whole area around Baekgok-ri had been prosperous place as a center of Buddhists’ culture in Shilla Kingdom along the west coast. In conclusion, structures, residences and storage pits were clustered centering around Gulgogaegil in the areas around the Dang Castle, as Dang Castle and Sangan-ri Relic I and II were utilized as spaces where military, political, and economic affairs were supervised. Baek Temple was located on the hill areas in Baekgok-ri connected to Sanga-ri and to the northeast. In the temple, a sanctuary serving Buddha statues and annexes were built. Classifying such events by period, Shilla Kingdom had conquered the area around Danghang Castle beginning from the middle of the 6th century to the mid of the 7th century and built the 1st Dang Castle. In the period, building sites 1 and 2, the octagon structure site, structure site with Ondol (floorheating system) at the lower level of the building site with stone pedestal were built there. It was the time when the transportation routes passing by the Sangan-ri Relics were arranged. In the latter times of the 7th to the 8th century, many building sites including rectangular sites and structure sites with stone pedestals were built in the 1st Dang Castle. It was the time when the Sangan-ri Relics began to form in full scale. Baekgok-ri Fortress was also built at that time. Baek Temple was built as well, which changed the landcape surrounding Dang Castle once again. In the 9th century, the 2nd Dang Castle was built along with many structures around a water collecting facility. It was assumed that, pits, porcelain kiln, and warehouse sites for storing goods were built in the areas ranging from Sanganri to Baekgok-ri. Porcelain kiln and the structure sites had been continuously used until the early Goryo Dynasty and roof tiles of Dang Castle were produced there. The landscape around Dang Castle and neighborhood reached its peak of the beauty at that time.