Bishop Hosius, who had been the ecclesiastical advisor to the late Constantine I, presides in the winter of 342-343 at the Council of Serdica (modern Sofia), which city had reached its greatest height under Constantine.

The council, called by Constans to settle the conflict between the orthodox Bishop Athanasius of Alexandria and the Arian Paul of Constantinople, achieves little, being boycotted by the Eastern bishops because the Westerners and the Egyptians insist on the presence of Athanasius the great defender of Trinitarian Christianity and the principal opponent of Arianism.

The Council of Philippopolis (held in 343, 344, or 347) is a result of Arian bishops from the Eastern Roman Empire leaving the Council of Sardica to form their own counter council.

In Philippopolis, they anathematize the term homoousios, in effect excommunicating Pope Julius as well as their rivals at the Council in Sardica, and introduce the term Anomoian.

As a result, the Arian controversy is perpetuated, rather than resolved, as had been the original intention of the emperors Constans and Constantius together with Julius, who had called the Council of Sardica.

A visit by Constans to Britain in the early months of 343 will turn out to be the last made by a legitimate emperor.

The speed of his trip, paired with the fact he had crossed the English Channel during the dangerous winter months, suggests it was in response to a military emergency of some kind, possibly to repel the Picts and Scots.

Shapur II, Sassanid ruler of the Persian Empire, has waged his campaign against Constantius II from 337, but it has so far been mostly unsuccessful.

Shapur had repelled Constantius’s invasion of Adiabene (Mesopotamia) in 343 but is unable to take the fortress of Singara in the siege of 344).

Chinese records first describe the Korean polity of Baekje as a kingdom in 345.

One source estimates three thousand monasteries dotting Egypt from north to south by the time of the death in 345 of Pachomius, the founder of cenobitic monasticism.

This number will grow within a generation after his death to seven thousand, then expand from Egypt into Palestine and the Judea Desert, Syria, North Africa and eventually Western Europe.

The emperor Constans, an ardent orthodox Christian, is known as a vigorous opponent of Arianism and paganism and a supporter of Athanasius, the Bishop of Alexandria.

Constans in 341 promulgates an edict banning pagan sacrifices and magic rituals under penalty of death.

In the contrast between the Nicene and Arian factions, Constans supports the former, while Constantius the latter.

Constans wins acceptance for a religious policy favorable to the Nicaeans, and secures the return of their leader, Athanasius, to Egypt, where the Alexandrians welcome him as a popular hero.

Ulfilas has worked for seven years among the Goths north of the Danube.

Because of persecution by the pagan ruler of the Thervings, he leads his congregation to …

…Moesia Secunda with the consent of the Arian Roman emperor Constantius II, Constantine’s middle surviving son, who rules the eastern provinces (Thrace, Macedonia, Greece, Asia, and Egypt).

Struggles within the Jie Later Zhao regime had resulted in the benefit of Ran Min, who by 350 CE has taken over the regime and massacred the entire ruling Shi family, with the exception of one cousin of Shi Jian, the last emperor of Later Zhao, who leads an uprising against him, beginning the Wei–Jie war.

Shi Jian's cousin, Shi Zhi, had been a Later Zhao general at Xiangguo.

On hearing that Ran Min had massacred the Shi family and declared himself emperor, Shi Zhi had raised a rebellion against Ran Min.

He is quickly joined by several other Later Zhao border armies, mostly composed of Jie soldiers and who despise Ran Min's rule, as well as many other Wu Hu nations.

When he hears of the Jie revolt against him, Ran Min issues his famous "extermination order", in which he calls on the Chinese to kill all the Wu Hu who had conquered them half a century earlier.

The effect is immense; some two hundred thousand Jie are killed in Yecheng (the Wei capital) in a few days, and brutal fighting breaks out between Chinese and Wu Hu throughout North China.

Meanwhile, Ran Min's army meets the main rebel forces under Shi Zhi and defeats them at the Battle of Yecheng.

In spring 351, Ran Min besieges Shi Zhi's capital Xiangguo.

Shi Zhi seeks aid from Former Yan's prince Murong Jun and is able to deal Ran a major defeat.

At this time, the Xiongnu soldiers in Yecheng rebel, capture his son Ran Yin, and surrender to Shi Zhi, who executes Ran Yin.

Ran Min is thought to be dead, but when he appears in Yecheng, the city is calmed.

Shi Zhi has his general Liu Xian besiege Yecheng, but Ran Min defeats Liu in battle and awes him so much that Liu agrees that once he returns to Xiangguo, he will kill Shi Zhi and surrender.

He does so and sends Shi Zhi's head to Ran Min, and Ran Min has Shi Zhi's head burned on a busy street in Yecheng.

Later Zhao is at its final end.

The city of Xiangguo is burned, and its population moved to Yecheng.

Following the victory at Xiangguo, Ran Min's forces proceed northwards and defeat two Later Zhao border armies.

Wherever he capture territory from the rebels, Ran Min's forces massacre any Wu Hu living there, burying them in large pits.

Some one hundred thousand are reputedly killed in this way.

Thousands of Wu Hu flee China or are killed.