신라 통일기 三邊守幢의 성립과 의미

A study on the Establishment and its meaning of the Sambyeonsudang(三邊守幢) in Unified Silla period

신라는 당과의 군사적 동맹을 통해 삼국통일이라는 대업을 이룰 수 있었다. 하지만 장기간의 전란 끝에 도래한 평화는 오래가지 못했다. 삼국통일의 토대로 작용했던 나당 동맹이 근본적인 모순과 갈등에 의해 전쟁국면으로 전환되었다. 당에 맞서 신라가 항전을 시작한 것이다. 나당 간의 전쟁이 본격화 되면서 신라는 대응력을 강화해 나아갔다. 당군과 전투시 전역이 확대되거나 패퇴할 경우 신라본토까지 침략받아 자칫 국가의 존립까지 위협받을 수도 있었기 때문이다. 당과 직접 대면하게 되는 한산주‧우수주‧하서주에 「한산변」‧「우수변」‧「하서변」이라는 첨병부대를 신설하였다. 문무왕 후반기(668~673)에 3개 군단은 개별적으로 존재하였던 것으로 판단된다. 「한산변」은 육상과 수상의 요충지인 임진강 유역 중성현(칠중성) 일대, 「우수변」은 비열홀 전투(681)가 전개되었던 삭정군, 「하서변」은 진흥왕대 달홀주가 설치되었고 금강산이라는 자연지리적 요건을 겸비한 고성군으로 추정된다. 「삼변수당」이라는 군단 명칭은 나당 전쟁이 종료되고 국경이 확정되기 전까지 등장할 수 없는 표현으로서 전쟁이 지속되던 문무왕대까지는 사용이 어려웠다. 6정이나 5주서가 최종적으로 신문왕대 마지막 군단이 두어져 완성된 것처럼, 3개 군단은 개별적으로 존재하다가 신문왕대 군단통합이 진행되면서 「삼변수당」으로 完編되었다고 할 수 있다. 신문왕대 9주 체제가 완비되고 ‘통일신라’라는 실질적 영역화가 진전된 후 지방제도 정비를 바탕으로 완성된 군사조직이었다.

Silla could realize a great achievement of the unification of the Three States through a military alliance with Tang. But the peace that came along after the long-lasting war did not last long. The Silla-Tang alliance that worked as the ground for the unification of the Three States did reveal its fundamental contradiction and conflict, which led to the war situation after all. Against Tang, Silla began its fighting. As the war between Silla and Tang became serious, Silla began to strengthen its power of confrontation. It is because the state’s existence itself might get threatened if the fight against Tang’s corps got extended or defeated, and it invaded even the mainland of Silla, too. In Hansanju‧Woosooju‧Haseoju which directly confronted Tang, it newly established advance guard units called 「Hansanbyeon」‧「Woosoobyeon」‧「Haseobyeon」. The document says they were installed in the 10th year of King Sinmun’s reign, but it is thought that it was maintained in the latter period of King Munmu (668~673)’s reign. It is estimated that 「Hansanbyeon」 should be around Jungseonghyeon (Chiljungseong) in the basin of Imjin River, the strategic point of land and water, 「Woosoobyeon」 may be Sakjeong-gun where Biyeolhol Battle (681) developed, and 「Haseobyeon」 should be Goseong-gun where Dalholju was installed in King Jinheung’s reign and geographical conditions like Mountain Geumgang were favorably secured. The name of corps as 「Sambyeonsudang」 could not be used for sure before the war ended and the border was fixed, so it could not be used until King Munmu’s reign when the war between Silla and Tang continued. As 6 jeong or 5 juseo was finally completed with the last corps installed in King Sinmun’s reign, about 「Sambyeonsudang」, too, it is thought that the three corps existed individually, and then, the names became unified in King Sinmun’s reign. In King Sinmun’s reign, the 9-ju system was completed, and the corps integration was realized, and after the practical localization of ‘unified Silla’ proceeded, a military organization appeared based on the maintenance of local systems.