Editing Balhae (section)

===War with the Tang dynasty===
[[Dae Joyeong]] died in 719 and was succeeded by his son, [[Dae Muye]] (Da Wuyi, r. 719–737). While Muye accepted Tang gifts and title upon his succession, he showed his independence by giving his father a posthumous [[temple name]], Gowang/Gaowang (high king). Muye adopted his own reign title in 720.{{sfn|Wang|2013|p=88}} In 721, the Tang asked Balhae for military support against the [[Khitan people|Khitans]] but they refused.{{sfn|Kim|2011a|p=350}} To check Balhae's influence, the Tang appointed a chieftain of the [[Heishui Mohe]] (Heuksu Malgal) as prefect of Bozhou (in modern [[Khabarovsk]]) in 722. In 725, the [[Andong Protectorate]] suggested stationing an army in the region. In response, Tang officials dispatched an administration staffed by the leaders of smaller tribes under the command of the [[Youzhou]] governor-general. Muye was convinced that the Heishui Mohe and the Tang were plotting to attack him and required a preemptive strike. He ordered his brother, [[Dae Munye]] (Da Wenyi), to attack the Heishui Mohe. Munye, who had stayed at the Tang capital as a hostage since the start of peaceful relations in 705, and understood the implications of attacking a Tang ally, was reluctant to carry out the order. He advised Muye to abandon the plan twice.{{sfn|Wang|2013|p=89}}{{sfn|Kim|2011a|p=349}}

{{blockquote|When Goguryeo was at its peak, the country had 300,000 elite soldiers. It resisted the Tang court and refused to submit itself to China. As soon as the Tang troops reached the country, however, Goguryeo was swept into the dust. Now the population of Balhae is several times less than that of Goguryeo. Yet you want to betray the Tang court. We must not do it.{{sfn|Wang|2013|p=89}}|[[Dae Munye]]}}

Muye paid his brother no heed and used his reluctance as pretext to remove Munye from command. Munye fled to the Tang dynasty. A Balhae envoy arrived at the Tang court in 732 requesting the execution of Munye. In response, the Tang secretly sent Munye to [[Central Asia]] while informing Muye that his brother had been banished to [[South China]]. The reality of events, however, leaked out, enraging Muye. A Balhae naval force led by [[Jang Mun-hyu]] (Zhang Wenxiu) attacked Dengzhou on the north shore of the [[Shandong Peninsula]] and killed its prefect.{{sfn|Wang|2013|p=89-90}}<ref>{{cite web |title= |script-title=ru:История государства Бохай |trans-title=History of the Bohai State |url=http://www.rezerv.narod.ru/history/ussur-bohaihist.htm |access-date=2025-05-18 |website=www.rezerv.narod.ru |language=ru}}</ref> Additionally, Dengzhou was the center of maritime trade routes in East Asia, and was the locale where both Silla and Balhae envoys stayed when coming to pay tribute to the Tang Emperor. As a result, Balhae's attack on Dengzhou was not merely motivated by geopolitical retaliation against the Tang but also out a of a desire to assert its newfound maritime prowess as well as prevent the Heishui Mohe from establishing trade relations with the Tang, which would have weakened Balhae's dominace of the northern trade routes. Balhae's successful attack on Dengzhou also demonstrates a surprising maritime prowess for a thirty-year old state, which had military naval vessels that could cross the sea as well as merchant vessels that could carry out trade activities.<ref>{{cite book |last1=Kim |first1=Eun Gug |chapter=An Enduring Window between North and South: Parhae and Silla |title=A New History of Parhae |date=2012 |publisher=Brill |pages=80–81}}</ref>

In response to the attacks, the Tang ordered Kim Chungsin, the nephew of [[Seongdeok of Silla]] and courtier in the Tang court, to return to [[Silla]] and organize an attack on Balhae. Chungsin excused himself from the request by asking to remain in China as the emperor's bodyguard. In his place, the Tang sent Kim Saran, a low ranking Sillan diplomat, and a Tang eunuch. Munye was also recalled to recruit soldiers in Youzhou. In the meantime, Balhae struck again, sacking the town of Mt. Matou (northwest of modern [[Shanhaiguan]]), and killing 10,000 Tang soldiers. The Balhae force raided and pillaged along the Liao River and the coast of the [[Liaodong Peninsula]]. In 733, Tang and Sillan forces attempted a joint attack on Balhae but were accosted by a blizzard that blocked all roads and killed half of the 100,000 Tang-Silla army, forcing them to abort the invasion.{{sfn|Wang|2013|p=90-91}} Muye continued to try to kill his brother. He sent an agent to [[Luoyang]] to plot the assassination of his brother. Munye was attacked in broad daylight near the Tianjin Bridge outside the imperial palace but escaped unharmed.{{sfn|Wang|2013|p=91}}