Northern Yan

Yan, known in historiography as the Northern Yan (407 or 409–436), Eastern Yan or Huanglong, was a dynastic state of China during the era of Sixteen Kingdoms. Some historians consider Gao Yun, a member of the Goguryeo royal family, to be the first Northern Yan monarch, while others consider Feng Ba of Han ethnicity to be the founder.

Background
Gao Yun was a descendant of the Goguryeo royal family. When the Former Yan captured the Goguryeo capital, Hwando in 342, they also captured several members of the royal family and moved them to Qingshan (青山, in modern Jinzhou, Liaoning), where Gao Yun was born and grew to become a minor general under the Later Yan. In 397, Gao Yun helped the Yan emperor, Murong Bao quell the rebellion of his son, Murong Hui. As a reward, Bao adopted him as his own son, changing his name to Murong Yun.

It was around this time when Murong Yun became friends with the general, Feng Ba. Feng Ba was a Han Chinese whose family was originally from Changle Commandery before his grandfather, Feng He (馮和) moved to Shangdang during the Disaster of Yongjia. Ba's father, Feng An (馮安) served as a military general under the Western Yan. After Later Yan conquered Western Yan in 394, the Feng clan resettled in Longcheng. Feng Ba appeared to have grew up under heavy Xianbei influence, as his nickname Qizhifa (乞直伐) suggests Xianbei origin.

In 401, Murong Yun's adoptive uncle, Murong Xi came to power, and he was described in records as a cruel and arbitrary ruler. Feng Ba and his brother, Feng Sufu were charged with crimes against Xi, forcing them to flee to the countryside where they were determined to overthrow him. In 407, as Murong Xi was holding a funeral for Empress Fu, Feng Ba and his conspirators took control of the capital Longcheng and acclaimed Murong Yun as their leader. Xi initially led an assault on Longcheng but then fled the battle alone in panic. After his forces collapsed, Xi was later found and executed by Yun.

Reign of Gao Yun and Feng Ba
The founding year of the Northern Yan is up to debate; some historians consider Feng Ba as the first ruler of Northern Yan while others assert that it was Gao Yun. The reason is that Gao Yun was a member of the Later Yan imperial family as Murong Bao's adopted son, and so he should be considered the last ruler of Later Yan. On the other hand, he was ethnically Goguryeo and reverted back to his old family name shortly after ascending. Thus, Northern Yan's founding year can either be 407 or 409.

Gao Yun took the title of Heavenly King. The Later Yan was previously at war with Goguryeo, but Yun managed to establish friendly relations between them and Northern Yan. However, conflict with the Northern Wei also began as the Yan Inspector of You Province, Murong Yi (慕容懿) defected to Wei. Worried by his lack of reputation, Yun attempted to protect himself by empowering his favourites, but in 409, two of them, Li Ban (離班) and Tao Ren (桃仁) assassinated him. Feng Ba's men then had the assassins killed, and the officials acclaimed him as the new Heavenly King.

The Northern Yan was relatively weak compared to Northern Wei, so Feng Ba formed good relations with the Eastern Jin, Hu Xia, Rouran, Khitan and Kumo Xi. He secured the support of his people by actively participating in politics, promoting agriculture and reducing tax burdens. However, he was also wary of handing out higher offices to his retainers, which led to a rebellion by his cousins in 410. On two occasions, Feng Ba had Wei envoys detained. In 416 and 418, Wei clashed with Yan, but due to pressure from stronger neighbours like the Hu Xia, they were unable to launch any substantial campaign throughout Feng Ba's reign. Northern Yan also continued Later Yan's dual administrative system between their Han Chinese and "Hu" subjects, as Feng Ba appointed his Crown Prince as the Grand Chanyu to supervise the tribes, along with introducing other offices to assist the Grand Chanyu.

Decline and fall
Feng Ba became deathly ill in 430. Conflict arose between his Crown Prince, Feng Yi (馮翼) and favourite concubine, Consort Song (宋夫人), who wanted her own son to inherit the throne. The situation soon leaked to Feng Ba's brother, the Prime Minister Feng Hong, who led his troops and took over the capital. Feng Ba died soon after, and Feng Hong took the throne for himself, slaughtering all of Feng Ba's sons including Feng Yi.

At the time, the Wei had dealt with the Hu Xia threat in the west and began focusing on conquering Northern Yan. From 432 onwards, Yan faced periodic attacks from Wei. In 433, a succession issue led to Feng Hong's sons handing over Liaoxi Commandery to Wei. Feng Hong refused to surrender and attempted to secure his position by allying with the Liu Song dynasty, even becoming a vassal to them in 435, but Wei continued their assault nonetheless. Finally, a major Wei invasion in 436 prompted Feng Hong to flee to Goguryeo for protection, ending the Northern Yan.

Feng Hong remained in Goguryeo until 438. While the Goguryeo king, Jangsu initially refused to hand him over to Wei, Feng Hong repeatedly offended him and tried to escape to Liu Song, resulting in Jangsu executing him and his sons. In Northern Wei, Feng Ba's granddaughter grew to become Empress Dowager Feng, an important figure in Wei's history. In 1965, the tomb of Feng Sufu was discovered in Beipiao, Liaoning, which contained the earliest extant of the double stirrup along with a unique duck-shaped glassware.