Editing Goguryeo (section)

====Fall====
In the summer of 666, [[Yeon Gaesomun]] died of a natural cause and Goguryeo was thrown into chaos and weakened by a succession struggle among his sons and younger brother.<ref name="Succession">{{cite book|last1=Yi|first1=Ki-baek|title=A New History of Korea|year=1984|publisher=Harvard University Press|isbn=978-0674615762|page=67|url={{GBurl|id=g2mdVwXpMzwC|p=67}}|access-date=2 August 2016|language=en}}</ref> He was initially succeeded as ''Dae Mangniji'', the highest position newly made under the ruling period of Yeon Gaesomun, by his oldest son [[Yeon Namsaeng]]. As Yeon Namsaeng subsequently carried out a tour of Goguryeo territory, however, rumors began to spread both that Yeon Namsaeng was going to kill his younger brothers [[Yeon Namgeon]] and [[Yeon Namsan]], whom he had left in charge at [[Pyongyang]], and that Yeon Namgeon and Yeon Namsan were planning to rebel against Yeon Namsaeng. When Yeon Namsaeng subsequently sent officials close to him back to Pyongyang to try to spy on the situation, Yeon Namgeon arrested them and declared himself ''Dae Mangniji'', attacking his brother. Yeon Namsaeng sent his son [[Gwon Saseong|Cheon Heonseong]] (泉獻誠), as Yeon Namsaeng changed his family name from Yeon (淵) to Cheon (泉) observe naming taboo for Emperor Gaozu, to Tang to seek aid. [[Emperor Gaozong of Tang|Emperor Gaozong]] saw this as an opportunity and sent an army to attack and destroy Goguryeo. In the middle of Goguryeo's power struggles between Yeon Gaesomun's successors, his younger brother, Yeon Jeongto, defected to the Silla side.<ref name="Succession" />

In 667, the Chinese army crossed the [[Liao River]] and captured Shin/Xin Fortress (新城, in modern [[Fushun]], [[Liaoning]]). The Tang forces thereafter fought off counterattacks by Yeon Namgeon, and joined forces with and received every possible assistance from the defector Yeon Namsaeng,<ref name="Succession" /> although they were initially unable to cross the Yalu River due to resistance. In spring of 668, Li Ji turned his attention to Goguryeo's northern cities, capturing the important city of Buyeo (扶餘, in modern [[Nong'an County|Nong'an]], [[Jilin]]). In fall of 668, he crossed the [[Yalu River]] and put [[Pyongyang]] under siege in concert with the Silla army.

Yeon Namsan and Bojang surrendered, and while Yeon Namgeon continued to resist in the inner city, his general, the Buddhist monk [[Shin Seong]] (信誠) turned against him and surrendered the inner city to Tang forces. Yeon Namgeon tried to commit suicide, but was seized and treated. This was the end of Goguryeo, and Tang annexed Goguryeo into its territory, with [[Xue Rengui]] being put initially in charge of former Goguryeo territory as protector general. The violent dissension resulting from Yeon Gaesomun's death proved to be the primary reason for the Tang–Silla triumph, thanks to the division, defections, and widespread demoralization it caused.<ref name="Graff200">{{cite book|last1=Graff|first1=David|title=Medieval Chinese Warfare 300–900|date=2003|publisher=Routledge|isbn=978-1134553532|page=200|url={{GBurl|id=gpmBAgAAQBAJ|p=200}}|access-date=6 November 2016|language=en}}</ref> The alliance with Silla had also proved to be invaluable, thanks to the ability to attack Goguryeo from opposite directions, and both military and logistical aid from Silla.<ref name="Graff200" /> The Tang established the [[Andong Protectorate]] on former Goguryeo lands after the latter's fall.{{sfn|Wang|2013|p=81}}{{sfn|Xiong|2008|p=43}}

However, there was much resistance to Tang rule (fanned by Silla, which was displeased that Tang did not give it Goguryeo or Baekje's territory), and in 669, following Emperor Gaozong's order, a part of the Goguryeo people were forced to move to the region between the Yangtze River and the Huai River, as well as the regions south of the Qinling Mountains and west of Chang'an, only leaving old and weak inhabitants in the original land. Over 200,000 prisoners from Goguryeo were taken by the Tang forces and sent to [[Chang'an]].<ref>{{cite book | last=Lewis | first=Mark Edward | title=China's cosmopolitan empire: The Tang dynasty | year=2009 | publisher=Harvard University Press | location=Cambridge | isbn=9780674033061}}</ref> Some people entered the service of the Tang government, such as [[Go Sagye]] and his son [[Gao Xianzhi]] (Go Seonji in Korean), the famed general who commanded the Tang forces at the [[Battle of Talas]].<ref>{{cite book|last1=Graff|first1=David|title=Medieval Chinese Warfare 300–900|date=2003|publisher=Routledge|isbn=978-1134553532|page=213|url={{GBurl|id=gpmBAgAAQBAJ|p=213}}|access-date=29 July 2016|language=en}}</ref><ref>{{cite book|last1=Grant|first1=Reg G.|title=1001 Battles That Changed the Course of World History|year=2011|publisher=Universe Pub.|isbn=978-0789322333|page=118|url={{GBurl|id=s4njwZGrZg4C|p=118}}|access-date=29 July 2016|language=en}}</ref><ref>{{cite book|last1=Starr|first1=S. Frederick|title=Xinjiang: China's Muslim Borderland|date=2015|publisher=Routledge|isbn=978-1317451372|page=38|url={{GBurl|id=XuvqBgAAQBAJ|p=38}}|access-date=29 July 2016|language=en}}</ref><ref>{{cite book|last1=Connolly|first1=Peter|last2=Gillingham|first2=John|last3=Lazenby|first3=John|title=The Hutchinson Dictionary of Ancient and Medieval Warfare|date=
2016|publisher=Routledge|isbn=978-1135936815|url={{GBurl|id=1LUoDAAAQBAJ|pg=PT263}}|access-date=29 July 2016|language=en}}</ref><ref>{{cite book|last1=Neelis|first1=Jason|title=Early Buddhist Transmission and Trade Networks: Mobility and Exchange Within and Beyond the Northwestern Borderlands of South Asia|date=2010|publisher=Brill|isbn=978-9004181595|page=176|url={{GBurl|id=GB-JV2eOr2UC|p=176}}|access-date=29 July 2016|language=en}}</ref>

Silla thus unified most of the Korean peninsula in 668, but the kingdom's reliance on China's Tang dynasty had its price. Tang set up the [[Protectorate General to Pacify the East]], governed by [[Xue Rengui]], but faced increasing problems ruling the former inhabitants of Goguryeo, as well as Silla's resistance to Tang's remaining presence on the Korean Peninsula. Silla had to forcibly resist the imposition of Chinese rule over the entire peninsula, which lead to the [[Silla–Tang War]]s, but their own strength did not extend beyond the [[Taedong River]].{{citation needed|date=January 2018}} Although the Tang forces were expelled from territories south of Taedong River, Silla failed to regain the former Goguryeo territories north of the [[Taedong River]], which were now under Tang dominion.<ref name=fuqua07-40>{{cite book | last=Fuqua|first=Jacques L. | title=Nuclear endgame: The need for engagement with North Korea|year=2007|publisher=Praeger Security International|location=Westport|isbn=9780275990749 | page=40}}</ref>