The founding of the Sassanian Empire in…

Remnants of the Jìn court flee south of the Chang Jiang River and reestablish the Jìn court at Jiankang, southeast of Luoyang and Chang'an and near modern-day Nanjing, under the Prince of Longya.

When the news of the fall of Chang'an reaches the south, the prominent local families of Zhu, Gan, Lu, Gu, and Zhou support the proclamation of the Prince as Emperor Yuan of the Eastern Jìn Dynasty.

(Because the emperors of the Eastern Jìn Dynasty thus spring from the Langye line, the rival Wu Hu states, which do not recognize its legitimacy, will at times refer to Jìn as "Langye.")

Constantine prevails again against his Eastern counterpart Licinius (shortly after he had named as co-emperor Valerius Valens, who had previously been dux limitis in Dacia) in the plain of Mardia (also known as Campus Ardiensis) in Thrace.

The emperors are reconciled after this battle.

Licinius according to a peace signed on March 1, 317, has to execute Valerius Valens, and cedes territory to Constantine, including …

…the provinces of Pannonia and Moesia.

Constantine had summoned to Trier the Christian theologian and polemicist Lactantius, to be the tutor of Crispus, who on March 1, 317, is given he title of caesar and made titular ruler of Gaul; Constantine's second son receives the title of Caesar at the same time.

The Diocese of Gaul (Latin: Dioecesis Galliarum, "diocese of the Gaul [province]s"), established in about 314, encompasses northern and eastern Gaul; that is, modern France north and east of the Loire, including the Low Countries and modern Germany west of the Rhine.

The diocese comprises the following provinces: Gallia Lugdunensis I, Gallia Lugdunensis II, Gallia Lugdunensis III, Gallia Lugdunensis IV (Senonia), Belgica I, Belgica II, Germania I, Germania II, Alpes Poenninae et Graiae and Maxima Sequanorum.

The Han Zhao, or Former Zhao, a state of the Sixteen Kingdoms during the Jin Dynasty, represents two state titles, the Han state proclaimed in 304 by Liu Yuan and the Former Zhao state in 319 by Liu Yao.

(The reason it is referred to as Former Zhao is that when its powerful general Shi Le breaks away and forms his own state in 319, he names it Zhao as well, and so Shi Le's state is referred to as Later Zhao.)

Although chronologically the Han Zhao is not the first of the Sixteen kingdoms, its armies had sacked the Jin dynastic capitals of Luoyang in 311 and Chang'an in 316.

Emperor Huai and Emperor Min of the Jin had been captured, humiliated and executed.

Remnants of the Jin court have fled to Jiankang, located eastward of Luoyang and Chang'an, and founded the so-called Eastern Jin Dynasty, under Sima Rui the Prince of Langye, who later becomes Emperor Yuan.

In 318, Liu Can and the ruling family residing at Pingyang had been toppled and executed by the coup d'etat of Jin Zhun, who is in turn eliminated by Shi Le and Liu Yao, who, as an imperial prince, claims the throne and changes the name of the state to Zhao.

Shi Le, of the Shi family of the Jie ethnicity, establishes Later Zhou, a state of the Sixteen Kingdoms during the Jin Dynasty, in 319.

The Later Zhao, with its capital at Xiangguo (in modern Xintai, Hebei), is the second, in territorial extent, to the Former Qin that once unified Northern China under Fu Jian.

One Athanasius, who seems to have been brought early in life under the immediate supervision of the ecclesiastical authorities of his native Alexandria, is educated classically and theologically here and ordained deacon and appointed secretary to Bishop Alexander.

Here, in the intellectual, moral, and political center of the ethnically diverse Greco-Roman world, he articulates in around 318 the orthodox doctrine of redemption in an early work, On the Incarnation of the Word.

A  presbyter named Arius comes into a direct conflict in about 319, with Alexander.

Arius appears to have approached Alexander for what he felt were misguided or heretical teachings being taught by the bishop.

Arius’ theological views appear to have been firmly rooted in Alexandrian Christianity, and his Christological views are certainly not at all radical.

He embraces a subordinationist Christology (that God did not have a beginning, but the Logos did), heavily influenced by Alexandrian thinkers like Origen, which is a common Christological view in Alexandria at this time.

Arius, in essence, denies the full deity of the preexistent Son of God who became incarnate in Jesus Christ.

He argues that God created the Son, while divine and like God ("of like substance"), as the agent through whom he created the universe.

Says Arius of the Son: "there was a time when he was not."

The Arianist creed as propounded by Arius holds that Christ, as the begotten Son of God, was created as other humans and that only the unbegotten God the Father is divine.

Constantine in 319 prohibits the separation of the families of slaves during a change in ownership.

The Zhang family of the Han Chinese ethnicity establishes Former Liang, a state of the Sixteen Kingdoms, in 320.

Its territories include present-day Gansu and parts of Ningxia, Shaanxi, Qinghai and Xinjiang.

All rulers of the Former Liang will remain largely titular under the court of the Jin dynasty as the Duke of Xiping except Zhang Zuo who proclaims himself "wang" (prince/king).

However, at times the other Former Liang rulers will also use the wang title when imposed on them when they are forced to submit to Han Zhao, Later Zhao, or, eventually, Former Qin.

Licinius has built up his army and accumulated a huge reserve of treasure during the years of uneasy peace between the Roman Empire’s two Augusti.

Having eventually become alienated from the Christians, he initiates a mild form of persecution in about 320, prompting contemporaries to paint the growing conflict between Constantine and his eastern counterpart as a battle between the forces of paganism and Christianity.