The Dingling, a Siberian people who originally lived on the bank of the Lena River in the area west of Lake Baikal, had begun to expand westward in the third century.

Some groups of Dingling also moved to China and settled there in the first century CE as early as during Wang Mang's reign, forming part of the southern Xiongnu tribes known as Chile during the third century, from which the later name Chile originated.

They adopted the last name Zhai.

The name "Chile" and "Gaoche" had first appeared in Chinese literature during the campaigns of Former Yan and Dai in 357 and 363 respectively.

However, the protagonists will be equally addressed as "Dingling" in the literary record of the Southern Dynasties.

Dingling leader Zhai Bin, who had rebelled against Former Qin's emperor Fu Jiān in 383, had supported Later Yan's founding emperor Murong Chui when Murong Chui rebelled against Former Qin as well and established Later Yan.

However, in 384, as Murong Chui is besieging the important city Yecheng, which is defended by Fu Jiān's son Fu Pi, Zhai Bin, seeing that Murong Chui is unable to capture the city quickly, begins to consider other options.

When, in particular, he requests a prime ministerial title from Murong Chui and is refused, Zhai Bin prepares to ally with Fu Pi instead, but his plan is discovered, and he is killed, along with his brothers Zhai Tan and Zhai Min.

It is apparently at this time that Zhai Bin’s son or nephew Zhai Liao and his cousin Zhai Zhen flee with some of their Dingling troops and resists Later Yan's subsequent campaigns to take the territory north of and around the Yellow River.

The strategically important city of Xiangyang, gateway to the Middle Yangtze, had fallen to Fu Jian in 379.

The controversial Murong Chui, a great general of the Chinese/Xianbei state Former Yan, had fled to Former Qin and become one of Fu Jian’s generals, participating in the campaign commanded by Fu Jian's son Fu Pi against Jin's key city of Xiangyang.

Fu Jian had conquered all of north China by 381 and began preparing for an invasion of the south.

In 382, when Fu Jian wanted to launch a major campaign to destroy Jin and unite China, most officials, including Fu Jian's brother Fu Rong, Duke of Yangping, who had succeeded Wang Meng as prime minister after Wang's death in 375, opposed, but Murong Chui and Yao Chang urged the campaign.

In May of 383, a Jin army of one hundred thousand commanded by Huan Chong attempts to recover Xiangyang but is driven off by a Qin relief column of fifty thousand men.

Fu Jian responds by ordering a general mobilization against Jin, conscripting one in ten able men and mustering thirty thousand elite guards.

In August, Fu Jian sends his brother Fu Rong with an advance force of three hundred thousand.

Later this month, Fu Jian marches with his army of two hundred and seventy thousand cavalry and six hundred thousand infantry from Chang'an, reaching Xiangcheng in September.

Separate columns are to push downstream from Sichuan, but the main offensive is to occur against the city of Shouchun on the Huai River.

Emperor Xiaowu of Jin, hurriedly preparing a defense, assigns Huan Chong responsibility for the defense of the Middle Yangtze.

To Xie Shi and Xie Xuan and the elite eighty thousand-strong Beifu Army is given the defense of the Huai River.

The Jin army’s overall military strategist, prime minister Xie An, lacks military abilities but calms the panicking officials and people by his example.

The Former Qin forces under Fu Rong capture the important Jin city of Shouyang (in modern Lu'an, Anhui) in October.

Fu Jiān, seeing a possibility of a quick victory, leaves his main force at Xiangcheng and leads eight thousand light cavalry to rendezvous with Fu Rong while dispatching the captured Jin official Zhu Xu as a messenger to try to persuade Xie Shi to surrender.

Instead, Zhu advises Xie Shi that fact the Former Qin force has not entirely assembled and that he should try to defeat the enemy’s advance forces.

Xie Xuan and Liu Laozhi, leading five thousand elite troops to engage the Former Qin advance force, scored an unexpected victory, killing fifteen thousand of the enemy troops.

In November, the Former Qin troops encamp west of the Fei River; the numerically inferior Jin forces halt east of the river, unable to advance.

Xie Xuan sends a messenger to Fu Rong, suggesting that the Former Qin forces retreat slightly west to allow Jin forces to cross the Fei River, so that the two armies can engage.

Most of Fu Jian’s generals oppose this plan, but Fu Jiān, planning to attack the Jin forces as they cross the river, overrules them.

Fu Rong agrees and orders a retreat but the Qin army, its morale low, panics when Zhu Xu manages to broadcast the false information that their retreating force has been defeated.

The retreat becomes a rout, and the generals Xie Xuan, Xie Yan, and Huan Yi cross the river to launch a major assault.

Fu Rong attempts to halt the retreat and reorganize his troops, but after becoming unhorsed, he is killed by Jin troops.

The Jin army continues their pursuit, and the entire Former Qin force collapses.

In the ensuing retreat, beset by famine and death from exposure and harried by the Jin army, the Former Qin force loses an estimated seventy to eighty percent of its strength.

The battle is considered one of the most significant in the history of China.

Almost the entire Former Qin army has collapsed, although the forces under Murong Chui's command remain intact, and Fu Jian, who had suffered an arrow wound during the defeat, has fled to Murong Chui.

Murong Chui's son Murong Bao and brother Murong De have both tried to persuade Murong Chui to kill Fu Jian while it is within his power to do so, but Murong Chui instead returns his forces to Fu Jian's command and returns to Luoyang with Fu Jian.

However, responding to a suggestion by his son Murong Nong, he plans a rebellion to rebuild the Yan state.

Murong Chui tells Fu Jian that he fears rebellion by the people of the Former Yan territory, and that it would be best if he were to lead a force to pacify the region.

Fu Jian agrees, despite opposition by Quan Yi, and Murong Chui leads the army to Yecheng, defended by Fu Pi.

They suspect each other, but neither ambushes the other.

When the Dingling chief Zhai Bin rebels and attacks Luoyang, defended by Fu Pi's younger brother Fu Hui, Fu Pi orders Murong Chui to put down Zhai's rebellion, and Fu Pi sends his assistant Fu Feilong to serve as Murong Chui's assistant.

On the way to Luoyang, however, Murong Chui kills Fu Feilong and his Di soldiers and prepares to openly rebel.

Meanwhile, despite his suspicions of Murong Chui, Fu Pi does not put under surveillance Murong Chui's son Murong Nong and nephews Murong Kai and Murong Shao, and the three flee from Yecheng and initiate a rebellion of their own.

Murong Chui, not yet in open rebellion against Former Qin, arrives at Luoyang in spring 384, but Fu Hui, hearing of Fu Feilong's death, refuses to welcome him.

Murong Chui then enters into an alliance with Zhai Bin, who urges him to take the imperial title.

Murong Chui refuses at this point (reasoning that he should welcome Murong Wei back as emperor) but accepts the title of Prince of Yan, formally breaking away from Former Qin and establishing Later Yan.

(All rulers of the Later Yan will declare themselves "emperors".)

Immediately, the struggle is on for Murong Chui to capture the territory that was formerly Former Yan's.

Both Murong Chui and Murong Nong quickly capture many cities, isolating Luoyang and …

…Yecheng.

Fu Pi tries to persuade him to stop his rebellion, but he refuses, and instead tries to persuade Fu Pi to leave Yecheng with his forces intact; Fu Pi refuses, and Murong Chui puts Yecheng under siege.

With Former Qin now facing further rebellion by Murong Chui's nephews Murong Hong and Murong Chong, and Yao Chang, in the west, Yecheng is not able to receive any reinforcements, but Murong Chui is still unable to capture it quickly.

When Zhai Bin, in disappointment over not being given a prime ministerial title, considers switching sides again to Former Qin, Murong Chui kills him.

Zhai Bin's nephew Zhai Zhen rebels against Later Yan, and for the next several years, while battling Former Qin remnants, Murong Chui will also have to battle Dingling forces under Zhai Zhen and later his cousins Zhai Cheng and Zhai Liao.

Zhai Liao is defeated in late 384 by Murong Chui's sons Murong Lin and Murong Nong and forced to flee to his cousin Zhai Zhen.

Zhai Zhen's subordinate Xianyu Qi assassinates him in 385 and attempts to take over, but the Zhai family strikes back and kills him; another cousin of Zhai Liao's, Zhai Cheng, succeeds Zhai Zhen, but many of their subordinates surrenders to Later Yan.

In fall 385, Murong Chui attacks Zhai Cheng, and Zhai Cheng's subordinate Xianyu De kills Zhai Cheng and surrenders.

The Dingling troops are largely slaughtered.

However, Zhai Liao escapes the massacre and seeks refuge with Teng Tianzhi, Jin's governor of Liyang prefecture (roughly modern Hebi, Henan).

Teng trusts Zhai Liao greatly, and Zhai Liao, taking advantage of Teng's overdedication to hunting and ignorance of his soldiers' needs, begins to develop relationships with soldiers.

The Former Qin state had begun to break apart following the disastrous Battle of Fei River in Fu Jian’s failed bid to unify China.

Fu Jian himself is killed in 385 by his former subordinate, Yao Chang, the founding emperor of Later Qin.

Murong Chui, briefly during early 385, also has to battle the forces of Jin, which has taken most of the territory south of the Yellow River and is in a temporary alliance with Fu Pi.

The future of his Later Yan state appears dim, but after moving north to pacify most of modern Hebei, Murong Chui is eventually able to take Yecheng late in 385 when Fu Pi abandons it and moves west. (Fu Pi, upon hearing that Fu Jiān had died earlier that year at Yao's hand, now declares himself emperor, but poses no further threat to Later Yan.)

While isolated pockets of Former Qin resistance remain, by the end of 385 later Yan is largely in control of the territory north of the Yellow River and east of Taihang Mountains.