뉴스레터

How much do we know about the ancient kingdom of Balhae that existed for 200 years as northern and southern states from the late 7th century to the early 10th century along with Silla? Let’s start a historical journey, focusing on primary historical records related to Balhae and newly discovered data. It will be fun to excavate the hidden stories in Balhae’s history while looking at the diversity of interpretation and importance of data.

Historical Data about the War between Balhae and Tang

Mu, the second king of Balhae, began the war with an attack on Dengzhou. The war escalated into an international conflict with the participation of Silla.

In 732, the 20th year of Gaewon, Muye sent his commander, Jang Mun-hyu, to attack Dengzhou administrator, Wijun, together with pirates. He sent Muye to Yuju to draft soldiers for subjugation while letting Kim Sa-ran draft troops in Silla to attack the southern frontier of Balhae. They returned without any military exploits as more than half of soldiers were frozen to death because of the rugged mountains, cold weather, and heavy snows. Muye, out of deep resentment, secretly sent envoys to Dongdo to let assassins attack Munye south of the Cheonjin Bridge, but Munye survived the attack. He ordered Hanambu to kill all of the foes.

二十年, 武藝遣其將張文休率海賊攻登州刺史韋俊. 詔遣門藝往幽州徵兵以討之, 仍令太僕員外卿金思蘭往新羅發兵以攻其南境. 屬山阻寒凍, 雪深丈餘, 兵士死者過半, 竟無功而還. 武藝懷怨不已, 密遣使至東都, 假刺客刺門藝於天津橋南, 門藝格之, 不死. 詔河南府捕獲其賊, 盡殺之.

“Old Book of Tang” 199 Ha, Bal Hae-jeon

Strife over Jurisdiction of Heishui Mohe

There were two reasons Balhae went to war against Tang. First, Balhae and Tang were in a dispute over the jurisdiction of Heishui Mohe. Heishui Mohe, one tribe of Mohe located North-East of Balhae, regularly informed Balhae of its exchange with Tang and Gokturk. In 726, however, Heishui Mohe asked Tang to accept its land as Heuksuju and its village as Heuksubu. King Mu of Balhae concluded that “because Heishui begged for Tang’s government positions, it is surely aiming to conspire with Tang to attack us from the front and the back” (Balhaejeon, “Old Book of Tang”). King Mu ordered his brother Dae Mun-ye to suppress Heishui.

Standoff between King Mu and His Brother, Dae Mun-ye

Dae Mun-ye opposed attacks on Heishui. From his earlier experience as Tang’s hostage, he expressed opposition, saying attacks on Heishui would amount to acts betraying Tang, making Tang the enemy and leading to a collapse overnight. It was a claim referring to a time in which even Goguryeo, with a 300,000-person army, confronted Tang and ended up collapsing. Thus, it would be reckless for Balhae, only a fraction of Goguryeo, to resist Tang. When King Mu tried to kill Dae Mun-ye out of exasperation, Dae Mun-ye fled to Tang after mid-730. Xuanzong accepted him as he acknowledged Tang’s authority.

Conflict between King Mu and Xuanzong

Here confrontation over how to deal with Dae Mun-ye, the second reason for the Balhae-Tang war, began in earnest. King Mu sent envoys to deliver the message of Munye’s feelings of guilt and asked him to be killed. After sending Mun-ye to Anseo, Xuanzong told King Mu that “[he] couldn’t kill Mun-ye as they were old acquaintances from the same remote region. He was sent to Yeongnam in exile; he already left” (Balhaejeon, “Old Book of Tang”). Upon hearing that, King Mu approached Xuanzong saying, “The powerful country should have shown confidence to others. But how could it reiterate lies? (Balhaejeon, “Old Book of Tang”). Despite King Mu’s blatant criticism, Xuanzong turned down the demand to kill Dae Mun-ye or return him.

War begun with Balhae's Preemptive Strike

Xuanzong accused Balhae of being ungrateful and threatened to attack unless Balhae were to repent. King Mu launched a preemptive attack on Dengzhou and its nearby area, which was Tang’s entry and departure port for Balhae. Dengzhou’s ruling place was the Dengzhou Castle (Bongrae, Shandong Province today), which was a natural stronghold over the sea. In September 732, the 20th year of Gaewon, King Mu ordered his commander, Jang Mun-hyu, to lead the Balhae army in attack, resulting in killing the administrator, Wijun. Given that Dengzhou’s defenders numbered 1,500 to 4,000, the number of Balhae’s attacking troops would have been more than that. Xuanzong sent Gae Boksun to launch counterattacks, but the Balhae army had already retreated.

The epitaph of Wijun discovered in Luoyang recently:
“Innocent island barbarians of Balhae crossed the ocean secretly, far away in the distance, and directly targeted the isolated castle.

He suddenly died at his official residence at the age of 57.”

『洛阳流散唐代墓誌彙编』, - 国家图书馆出版社，2013

Bloody Battle between King Mu and Dae Mun-ye

King Mu of Balhae appeared in Yuju in person (today’s Beijing and its nearby area) where Dae Mun-ye had been sent to fight. King Mu led soldiers to Mado Mountain to attack the castle; the pit built with big stones that blocked the main artery by Oh Seungche is said to have extended 400 ri (Ohseungchejeon, “New Book of Tang”). Considering that King Mu attacked Mado Mountain right after its strike on Dengzhou in September 732, there would have been a bloody battle between King Mu and Dae Mun-ye

Balhae-Tang-Silla war 732-735

Silla King Seongdeok’s Participation in the War and Acquisition of the Region South of the Pae River

Xuanzong, on the other hand, ordered Kim Sa-ran to be brought back to let Silla attack the southern area of Balhae. Four generals, including Kim Yu-sin’s grandsons Yun Jung and his younger brother Yun Mun, embarked to attack Balhae with Tang’s soldiers. It appears that the allied forces started near the Pae River (Taedong River today), passed through the highlands of the entrance to Pyeongan-do Province and Yalu River, and headed towards Seogyeongaprokbu, an important spot on the way to Tang. More than half of the soldiers were frozen to death because of the rugged mountains, cold weather, and heavy snows. The allies had no choice but to retreat with no victory as a result. Silla proposed Tang that they would attack Balhae again in 734, but to no avail. Silla was obliged to participate in the Balhae-Tang conflict and received the land south of the Pae River in 735, albeit perfunctorily.

Postwar Readjustment and Reestablishment of Balhae-Tang Relations

After failing to vent his spite against Dae Mun-ye through war, King Mu even sent assassins, but to no avail. Both countries moved towards reconciliation around March 735 (the 23rd year of Gaewon). The younger brother (Daebeon) of the king of that time, King Mu, entered Tang for the first time since the war, and it may have been the dispatch of envoys for reconciliation. Their postwar readjustment ended with the exchange of prisoners. Xuanzong’s praised records show that King Mu of Balhae repatriated Tang’s sailors and prisoners through Damonggo (“Quantangwen” volume 285). The Balhae-Tang relationship made a fresh development as King Mun, son of King Mu, ascended the throne.