The Mahan(馬韓) society formed based on early iron culture in the
4th century B.C.. The central area south of Noryong(蘆嶺) was located
at the tributaries of the Youngsan River, with the Yeongam, Hwasun
and Hampyong. The center of Mahan was moved to the coastal area
on the southwest sea as foreign trade increased and coastal routes were
activated along with expansion of the iron culture.
Haenam Peninsula was located at a strategic point which could
control ancient coastal routes connecting Korea to China and Japan
while Gungokri, which was looated in the Baekpoman Basin, became
a central stage for foreign trade as a port of call.
Around the middle of the second century in Samhan Society,
Nakranggun weakened followed by declining influence of King Jin(辰
王) of Mokji, and Baekje, Anya and Guya appeared. In the
southwestern sea, Sinunsin, which was located at Baekpoman Bay, in
Haenam stood out.
The background where Sinunsin grew and developed was that there
was increased marine activities and colder weather. It was discovered that the Mahan society in the southwestern area achieved great
socio-economic development in consideration of its community
structure, housing sites and the methods of tomb construction. Mahan
society in the southwestern area showed further development in foreign
exchange with the Western-Qin(西晉). Sinmi went to Dongigyowebu(東
夷校尉府) located at Liaoyang via Daebang and Nakrang while leading
twenty small nations which were located in the southwestern area and
the Youngsan River basin.
Sinmi began to step towards formation of the League by leading
foreign exchanges between the small nations which were distributed in
the southwestern area and the Youngsan River basin. It lost the external
impetus necessary for formation of the league as the international
environment changed due to the destruction of the West Qin, collapse
of Dongigyowebu and expulsion of Nakrang and Daebang. After
Nakrang was expelled, the group which dominated the leadership of
marine activities in the southwestern area was Chimmidarye(忱彌多禮).
Chimmidarye incorporated the Mahan society area south of Noryong
while opposing pressure from Baekje advancing south to put all the
southwestern area of Jeonbuk(全北) under its influence. He prepared
this against Baekje’s advance by building Oknyobong Fortress and
Ilpyongri Fortress as Baekje’s pressure to move south accelerated.
Finally, he gave up Oknyobong Fortress and made a final stand at
Hyonsan Fortress, Geumswedong, Gusiri, and Hyonsanmyon.
Baekje’s advance into Mahan ended when it incorporated Biri(比利)
and Byokjung(辟中) in the southwestern area in Jeonbuk after it
slaughtered Chimmidarye via Gohaejin, Gangjin. Baekje had controling power over the sea trade routes connecting to Gaya and Japan with
aboriginal marine forces after dominating the southwestern area
including Chimmidarye.