Dongdan Kingdom (東丹, Khitan language

Khitan language

The Khitan language is a now-extinct language once spoken by the Khitan people . Khitan is generally deemed to be genetically linked to the Mongolic languages. It was written using two mutually exclusive writing systems known as the Khitan large script and the Khitan small script...

:Dan Gur, Chinese: 东丹, Korean:동단) was the puppet kingdom

Puppet state

A puppet state is a nominal sovereign of a state who is de facto controlled by a foreign power. The term refers to a government controlled by the government of another country like a puppeteer controls the strings of a marionette...

 established by the Khitan

Khitan people

thumb|250px|Khitans [[Eagle hunting|using eagles to hunt]], painted during the Chinese [[Song Dynasty]].The Khitan people , or Khitai, Kitan, or Kidan, were a nomadic Mongolic people, originally located at Mongolia and Manchuria from the 4th century...

 to rule the realm of the Balhae

Balhae

Balhae was a Manchurian kingdom established after the fall of Goguryeo. After Goguryeo's capital and southern territories fell to Unified Silla, Dae Jo-yeong, a Mohe general, whose father was Dae Jung-sang, established Jin , later called Balhae.Balhae occupied southern parts of Manchuria and...

 in Eastern Manchuria

Manchuria

Manchuria is a historical name given to a large geographic region in northeast Asia. Depending on the definition of its extent, Manchuria usually falls entirely within the People's Republic of China, or is sometimes divided between China and Russia. The region is commonly referred to as Northeast...

.

After conquering the Dan Gur (Balhae in Khitan language) in 926, the Khitan crown prince Yelü Bei

Prince Bei

Prince Bei, fully Yelü Bei , officially Emperor Yizong of Liao , was the eldest son of Abaoji, the founder of the Liao Dynasty. He was declared successor to the first emperor of the Liao Empire in 916, but never succeeded to the throne...

 ascended to the throne of it at the Holhan fortress, the capital of Balhae, today's Mudanjiang, Heilongjiang Province. It used Dongdan as its Chinese name, which means the east Dan Gur, in respect to the West Liao dynasty

Liao Dynasty

The Liao Dynasty , also known as the Khitan Empire was an empire in East Asia that ruled over the regions of Manchuria, Mongolia, and parts of northern China proper between 9071125...

.

However, political tension soon evolved between Yelü Bei and his younger brother Yelü Deguang

Emperor Taizong of Liao

The Emperor Taizong of Liao , born as Yelü Deguang , was the second emperor of the Khitan Empire .-Succession to the Throne:...

, who took the imperial throne of Khitan after their father Yelü Abaoji

Emperor Taizu of Liao

The Emperor Taizu of Liao was the first emperor of the Liao Dynasty . His given name was Abaoji . Some sources also suggest that the surname Yelü was adopted during his lifetime, though there is no unanimity on this point....

 died, en route to his homeland from a relatively successful campaign against the Later Tang Dynasty

Later Tang Dynasty

The Later Tang Dynasty was a short-lived dynasty that lasted from 923 to 937 one of the five dynasties during the Five Dynasties and Ten Kingdoms Period. It was also the first in a series of three dynasties ruled by the Shatuo Turks...

. The new emperor ordered his elder brother to move his capital from Huhan in Eastern Manchuria to Liaoyang

Liaoyang

Liaoyang is a city in China, Liaoning province, located in the middle of the Liaodong Peninsula. The city is situated on the T'ai-tzu River and forms with Anshan a built up area of 2,057,200 inhabitants in 2010....

 in Western Manchuria.

Bei obeyed the imperial order but soon fled to North China to avoid possible assassination in 930. Bei's son was elevated to the new king of Dongdan, but the kingdom was annexed by the Liao Dynasty

Liao Dynasty

The Liao Dynasty , also known as the Khitan Empire was an empire in East Asia that ruled over the regions of Manchuria, Mongolia, and parts of northern China proper between 9071125...

 in 936.

To continue Balhae's friendly relations with Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, Dongdan sent a diplomatic mission over the Sea of Japan

Sea of Japan

The Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...

 (East Sea) in 929. But the Japanese court in Kyoto

Kyoto

is a city in the central part of the island of Honshū, Japan. It has a population close to 1.5 million. Formerly the imperial capital of Japan, it is now the capital of Kyoto Prefecture, as well as a major part of the Osaka-Kobe-Kyoto metropolitan area.-History:...

rejected the mission from Dongdan.