David Keys ' book speculates that the climate changes may have contributed to various developments, such as the emergence of the Plague of Justinian, the decline of the Avars, the migration of Mongolian tribes towards the West, the end of the Persian Empire, the rise of Islam, and the fall of Teotihuacán.

He sanctioned a code of laws for Great and Lesser Poland, which gained for him the title of " the Polish Justinian " and founded the University of Kraków which is the oldest Polish university, although his death temporarily stalled the university's development ( which is why it is today called the " Jagiellonian " rather than " Casimirian " University ).

The great monastery of Dafni, that was built under Justinian I's rule, is an isolated case that does not signify a widespread development of Attica during the Byzantine period.

Hellenistic theology, which could be deemed to last until the suppression of the Athenian Academy in 529 by Justinian I, overlaps with early Jewish and early Christian theology ( see below ), and several strands of thought important particularly to early Christian thought arise within Hellenistic circles: attempts to explain the apparent caprice of the gods, Atheism, the development of monotheism, the idea of God as first cause or form of the Good, the dualism of spirit and matter in humanity, and redemption ( the release of the spirit from its material prison to a higher spiritual world ) through knowledge.

The Ghassanid king al-Harith ibn Jabalah ( reigned 529 – 569 ) supported the Byzantines against Sassanid Persia and was given the title patricius in 529 by the emperor Justinian I. Al-Harith was a Miaphysite Christian ; he helped to revive the Syrian Miaphysite ( Jacobite ) Church and supported Miaphysite development despite Orthodox Byzantium regarding it as heretical.

The Emperor Justinian I's formation of a new code of law, the Corpus Juris Civilis, served as a basis of subsequent development of legal codes.

The basic principles of the Pentarchy theory, which, according to the Byzantinist historian Milton V. Anastos, " reached its highest development in the period from the eleventh century to the middle of the fifteenth ", go back to the 6th-century Justinian I, who often stressed the importance of all five of the patriarchates mentioned, especially in the formulation of dogma.

This article includes the advances in technology and the development of several engineering arts before the Middle Ages, which began after the fall of the Western Roman Empire in AD 476, the death of Justinian I in the 6th century, the coming of Islam in the 7th century, or the rise of Charlemagne in the 8th century.

At about that time Justinian II established the first new guards units to protect the imperial palace precinct, while in the 8th century the emperors, faced with successive revolts by the thematic armies and pursuing deeply unpopular iconoclastic policies, established the imperial tagmata as an elite force loyal to them.

In 554, Eastern Roman Emperor Justinian I reconquered Italia keeping in general the organization of Diocletian.

* 527 – Justinian I becomes the sole ruler of the Byzantine Empire.

The regnal year of the emperor was also used to identify years, especially in the Byzantine Empire after 537 when Justinian required its use.

The region was then ruled by the Ostrogoths up to 535, when Justinian I added the territory to the Byzantine Empire.

Isidore of Miletus was a renowned scientist and mathematician before Emperor Justinian I hired him, “ Isidorus taught stereometry and physics at the universities, first of Alexandria then of Constantinople, and wrote a commentary on an older treatise on vaulting .” Emperor Justinian I appointed his architects to rebuild the Hagia Sophia following his victory over protesters within the capital city of his Roman Empire, Constantinople.

Isidore of Miletus and Anthemius of Tralles originally planned on a main hall of the Hagia Sophia that measured 230 feet by 250 feet, making it the largest church in Constantinople, but the original dome was nearly 20 feet lower than it was constructed, “ Justinian suppressed these riots and took the opportunity of marking his victory by erecting in 532-7 the new Hagia Sophia, one of the largest, most lavish, and most expensive buildings of all time .” Although Isidore of Miletus and Anthemius of Tralles were not formally educated in architecture, they were scientists that could organize the logistics of drawing thousands of laborers and unprecedented loads of rare raw materials from around the Roman Empire to create the Hagia Sophia for Emperor Justinian I.

During his reign, Justinian sought to revive the Empire's greatness and reconquer the lost western half of the classical Roman Empire.

As a Christian Roman emperor, Justinian considered it his divine duty to restore the Roman Empire to its ancient boundaries.

From his uncle, Justinian inherited ongoing hostilities with the Sassanid Empire.

Having thus secured his eastern frontier, Justinian turned his attention to the West, where Arian Germanic kingdoms had been established in the territories of the former Western Roman Empire.

Emperor Justinian reconquered many former territories of the Western Roman Empire, including Italy, Dalmatia, Africa, and southern Hispania.

In his efforts to renew the Roman Empire, Justinian dangerously stretched its resources while failing to take into account the changed realities of 6th-century Europe.

Justinian also strengthened the borders of the Empire from Africa to the East through the construction of fortifications, and ensured Constantinople of its water supply through construction of underground cisterns ( see Basilica Cistern ).

In order to bypass the Persian landroute, Justinian established friendly relations with the Abyssinians, whom he wanted to act as trade mediators by transporting Indian silk to the Empire ; the Abyssinians, however, were unable to compete with the Persian merchants in India.

In Civilization IV, Justinian is the leader of the Byzantine Empire.

The Emperor Justinian and the Byzantine Empire.

Nor did its Germanic traditions offer any code of civil law required of urbanised society, such as Justinian I caused to be assembled and promulgated in the Byzantine Empire.

A period of instability then ensued, tempting the Eastern Roman Emperor Justinian to declare war on the Ostrogoths in 535 in an effort to restore the former western provinces of the Roman Empire.

The Liber Pontificalis records that the following year John obtained valuable gifts as well as a profession of orthodox faith from the Byzantine emperor Justinian I the Great, a significant accomplishment in light of the strength of Monophysitism in the Byzantine Empire at that time.

After the dissolution of the Western Roman Empire, the Justinian Code remained in effect in the Eastern empire, known in the modern era as the Byzantine Empire ( 331 – 1453 ).

The codes of Justinian, particularly the Corpus juris civilis ( 529-534 ) continued to be the basis of legal practice in the Empire throughout its so-called Byzantine history.

Roman law as preserved in the codes of Justinian and in the Basilica remained the basis of legal practice in Greece and in the courts of the Eastern Orthodox Church even after the fall of the Byzantine Empire and the conquest by the Turks, and also formed the basis for much of the Fetha Negest, which remained in force in Ethiopia until 1931.

In 554, Granada and southernmost Hispania Baetica were lost to representatives of the Byzantine Empire ( to form the province of Spania ) who had been invited in to help settle a Visigothic dynastic struggle, but who stayed on, as a hoped-for spearhead to a " Reconquest " of the far west envisaged by emperor Justinian I.

Justinian commissioned Anthemius of Tralles and Isidore of Miletus to replace it with a new and incomparable St Sophia.

Justinian also had Anthemius and Isidore demolish and replace the original Church of the Holy Apostles built by Constantine with a new church under the same dedication.

* 532 – Byzantine Emperor Justinian I orders the building of a new Orthodox Christian basilica in Constantinople – the Hagia Sophia.

Emperor Justinian I ensured that his new structure would not be burned down, like its predecessors, by commissioning architects that would build the church mainly out of stone, rather than wood, “ He compacted it of baked brick and mortar, and in many places bound it together with iron, but made no use of wood, so that the church should no longer prove combustible .”

When Emperor Anastasius died in 518, Justin was proclaimed the new Emperor, with significant help from Justinian.

The destruction that had taken place during the revolt provided Justinian with an opportunity to tie his name to a series of splendid new buildings, most notably the architectural innovation of the domed Hagia Sophia.

Furthermore, Justinian restored cities damaged by earthquake or war and built a new city near his place of birth called Justiniana Prima, which was intended to replace Thessalonica as the political and religious center of the Illyricum.

Justinian also tried to find new routes for the eastern trade, which was suffering badly from the wars with the Persians.

After Scupi was almost completely destroyed by an earthquake in 518 AD, Justinian, according to his historian Procopius in " De Aedificiis " ( On the Buildings ), built a new city near his birthplace Tauresium and Bederiana ( believed to be today's villages Taor and Bader ) at the fertile entry point of the River Lepenec into the Vardar, making Skopje the city of Justiniana Prima.

* February 23 – Emperor Justinian I orders the building of a new Orthodox Christian basilica in Constantinople – the Hagia Sophia.

It was through the use of the restored Justinian code that Frederick came to view himself as a new Roman emperor.

With the help of his new troops, Justinian won a battle against the enemy in Armenia in 693, but they were soon bribed to revolt by the Arabs.

It has been suggested that the 681 peace treaty with the Byzantine Empire that established the new Bulgarian state was concluded at Varna and the first Bulgarian capital south of the Danube may have been provisionally located in its vicinity — possibly in an ancient city near Lake Varna's north shore named Theodorias ( Θεοδωριάς ) by Justinian I — before it moved to Pliska 70 km to the west.

In the sixth century under Emperor Justinian I the city was extended with new public buildings.

In 528, Emperor Justinian I created the new province of Theodorias out of the coastal belt around Laodicea, which was rebuilt and fortified against the increasing Persian threat.

During the reign of Emperor Justinian I, with increasing military threats and the expansion of the Eastern Empire, three new posts were created: the magister militum per Armeniam in the Armenian provinces, formerly part of the jurisdiction of the magister militum per Orientem, the magister militum per Africam in the reconquered African provinces ( 534 ), with a subordinate magister peditum, and the magister militum Spaniae ( ca.

Emperor Alexios I Komnenos ( 1081 – 1118 ) established a new military force from the ground up, which was directly responsible for transforming the aging Byzantine Empire from one of the weakest periods in its existence into a major economic and military power, akin to its existence during the golden age of Justinian I.

Some of the senators saw this as an opportunity to overthrow Justinian, as they were opposed to his new taxes and his lack of support for the nobility.

They conspired to overthrow the Emperor: if the plot had been successful, Justinian would have become the new Emperor.

He became a successful lawyer in Constantinople, and was appointed by Justinian in 528 as one of the commissioners to prepare the new imperial legal code, the Corpus Juris Civilis, released in 529.

In 534 the full Codex Justinianus was released, along with a series of new laws created by Justinian to reflect contemporary needs ( the Novellae ).

Around 555, according to Procopius, Emperor Justinian ( 527-565 ) renovated the fortifications of Nikopolis, as part of his huge program involving the renewal of city fortifications and the erection of new defences.