Since 668, Silla, on the eve of the Silla-Tang War, directly and indirectly supported the Goguryeo’s restoration uprising in the northwest side of Korean Peninsula, in addition to the accumulated discontent with the Tang’s Jimifuzhou(羈縻府州) system, which was based on the division and coexistence of the old three kingdoms, and strategically arranged to undermine it and erode its influence. Accordingly, various refugee groups joined forces through An-seung(安勝), the successor who guaranteed the legitimacy of the Goguryeo kingdom under Silla’s support and investiture, leading to the establishment of the “Hansung Goguryeo State(漢城 高句麗國)” in early 670. From Silla’s perspective, it was able to gain the practical strategic advantage of stabilizing the northern front for a considerable period of time through its connection and support with this Hansung Goguryeo State. In addition, it played an important role as an ideological device that allowed it to flaunt Silla-centered hegemony and moral legitimacy both domestically and internationally, at least within the Korean Peninsula. However, as the Tang army began its full-scale offensive in 672-673, Hanseong Goguryeo State lost its original base and its remaining forces flowed into Silla territory. In order to control them smoothly, Silla encamped them in Geummajeo(金馬渚, Iksan), and in 674, An-seung was re-appointed as ‘the King of Bodeok(報德王)’ from ‘the King of Goguryeo(高句麗王)’, further clarifying the hierarchy. This can also be understood as a measure to maximize the ceremonial and ideological value of Silla as a symbol of ‘dignity and virtue’ that subjugated Bodeok State(報德國), replacing the strategic value that was no longer expected due to the change in circumstances.
Afterwards, as the Silla-Tang War ended in a form that was virtually a victory for Silla, the handling of Bodeok State began to emerge as an important agenda. However, unlike King Munmu, King Sinmun took a radical approach of complete dissolution and assimilation in the Bodeok State administration in accordance with the political orientation of centralization and bureaucratization immediately after his ascension to the throne, triggered by the purge of the Kim Heumdol’s faction. This meant that while internally establishing a centralized bureaucratic system, externally seeking to resolve the Goguryeo refugee and restoration movement issue in order to improve diplomatioc relations with Tang. However, this measure escalated into a large-scale rebellion by the People of Bodeok Stronghold(報德城民) in 684. Although the rebellion itself was suppressed by force, it became an turning point to recognize the explosive power of the old Three Kingdoms refugee consciousness that still remained strong. Therefore, even after the suppression of the rebellion, Silla adopted not only a hard-line policy but also a moderate policy toward the People of Bodeok Stronghold, and thoroughly blocked connections between various resident groups based on Silla-centered standards, making surveillance and control easier. On the other hand, under such political necessity, the unified ideology centered on Silla was also able to develop into a more specific and refined form.