information:classification
Early history

Settlement of the Han River area, where present-day Seoul is located, began around 4000 BC.

Seoul is first recorded as Wiryeseong, the capital of Baekje (founded in 18 BC) in the northeastern area of modern Seoul. There are several city walls remaining in the area that date from this time. Pungnaptoseong, an earthen wall located southeast Seoul, is widely believed to have been at the main Wiryeseong site. As the Three Kingdoms competed for this strategic region, control passed from Baekje to Goguryeo in the 5th century.

However, according to Samguk Sagi, both Baekje and Silla described the land as frontier border of Baekje, not as the capital region. Moreover, Jinheung Taewang Stele found at current day Bukhansan tells that the place was underdeveloped as of 6th century AD, suggesting that the first capital Wiryeseong was not located in or nearby Seoul.

In July or August 553, Silla took the control of the region from Baekje, and the city became a part of newly established Sin Province (신주; 新州). Sin (新) has both meaning of "New" and "Silla", thus literally means New Silla Province.

In November 555, Jinheung Taewang made royal visit to Bukhansan, and inspected the borderline. In 557, Silla abolished Sin Province, and established Bukhansan Province (북한산주; 北漢山州). The word Hanseong (한성; 漢城; lit. Han Fortress) appears on the stone wall of "Pyongyang Fortress", which was presumably built in the mid to late 6th century AD over period of 42 years, located in Pyongyang, while there is no evidence that Seoul had name Hanseong dating the three kingdoms and earlier period.

In 568, Jinheung Taewang made another royal visit to the northern border, visited Hanseong, and stayed in Namcheon on his way back to the capital. During his stay, he set Jinheung Taewang Stele, abolished Bukhansan Province, and established Namcheon Province (남천주; 南川州; South River Province), appointing the city as the provincial capital. Based on the naming system, the actual name of Han River during this time was likely Namcheon (Nam River) itself or should have the word ending with "cheon" (천; 川) not "gang" (강; 江) nor "su" (수; 水). In addition, "Bukhansan" Jinheung Stele clearly states that Silla had possession of Hanseong (modern day Pyongyang), thus Bukhansan has to be located north of Hanseong. Modern day Pyongyang was not Pyongyang, Taedong River was likely Han River, and Bukhansan was not Bukhansan during the three kingdoms period. Moreover, Pyongyang was a common noun meaning capital used by Goguryeo and Goryeo dynasties, similar to Seoul.

In 603, Goguryeo attacked Bukhansanseong (북한산성; 北漢山城; Bukhan Mountain Fortress), which Silla ended up winning. In 604, Silla abolished Namcheon Province, and reestablished Bukhansan Province in order to strengthen the northern border. The city lost its provincial capital position and was put under Bukhansan Province once again. This further proves that Bukhansan was located in the North of modern-day Pyongyang as changing the provincial name and objective would not be required if Bukhansan was located within Seoul.

In the 11th century Goryeo, which succeeded Unified Silla, built a summer palace in Seoul, which was referred to as the "Southern Capital". It was only from this period that Seoul became a larger settlement.