Throughout the fifth century, Hellenistic-Eastern political systems, philosophies, and theocratic Christian concepts had gained power in the Greek-speaking Eastern Mediterranean due to the intervention of important religious figures there such as Eusebius of Caesarea () and Origen of Alexandria () who had been key to developing the constant Christianized worldview of late antiquity.
By the 6th century, such ideas had already influenced the definitive power of the monarch as the representative of God on earth and of his kingdom as an imitation of God's holy realm. The Byzantine Empire was a multi-ethnic monarchic theocracy adopting, following, and applying the Christian Orthodox-Hellenistic political systems and philosophies. The monarch was the incarnation of the lawnomos empsychosand his power was immeasurable and divine in origin insofar as he channeled God's divine grace, maintaining what is good. He was the ultimate benefactor, caretaker, and saviour of the people: Evergétis, Philanthrōpía, and Sōtēr, anointed with all power, upholding the divine laws since he ought to emulate Christ first (christomimetes) in all of his divine, pious, loving orthodox attributes to all by being his earthly presence.
The people in turn were the monarch's paroikoi (subjects). He was the sole administrator and lawgiver of the holy Basileia and Oikoumene (commonwealth), with sole power over the state, the land, and his subjects, which he had achieved through God's appointment of him as king. This opened a new stage of reverence in which Hellenistic and Eastern court ceremonies such as proskynesis highlighted the divinity of the ruler and became standardized and often mandatory. In practice, imperial power was exercised as administrationsimplified and centralized through viceroys such as the Exarchos, Douk, Katepánō, Kephalai and the Strategoi who enjoyed the same omnipotence and the emperor's God given dignity in their respective governorships.
Such concentrations of power proved to be both an internal weakness and the cause of various coups and rebellions in which viceroys with provincial armies and, sometimes, entire themes, would often challenge imperial power with claims of their own. In this way emperors such as Nikephoros II Phokas () and Heraclius () achieved royal power for themselves.
There were no codified laws on the imperial succession, and the Roman Republic was never formally abolished. Theoretically, each emperor was formally elected, by both the senate (Synkletos) and the army. In practice, however, the Senate had lost all of its former powers and was mostly reduced to a ceremonial role, filled with relatives or close aristocrats to the Emperor; while the Army practically had a monopoly regarding elections. Emperors usually managed to secure succession for their children through indirect means, such as appointing them as co-emperors, and thus introduced various dynasties. The absence of codified succession laws and procedures, as well as the militarized state of the Empire, led to a number of coups and revolts, leading to several disastrous results, such as the 1071 defeat at Manzikert.
Applying Christian Orthodox-Hellenistic administrative schemes, the monarch's household was the sacred kingdom Oikonomia, and he was its Christ-loving owner and manager Oikonomos, which meant that no individual or institution through the history of the empire truly owned any land in the face of state supreme ownership. Beneath the emperor, a multitude of officials and court functionariesall directly chosen by the emperor or by one of his representativesoperated the empire's administrative bureaucracy. State officials acted not as magistrates or elected public legates, but as representatives, deputies, and viceroys of the monarch in his different domains throughout the empire. In addition to those officials, a number of honorific titles existed, which the emperor awarded to prominent subjects or to friendly foreign rulers.
Over the more than a thousand years of the empire's existence, the Imperial administrative system evolved in its adoption of historic titles. At first, the various titles of the empire were the same as those of the late Roman Empire. However, by the era of Heraclius (), a number of the titles had become obsolete. By the time of Alexios I (), a number of the positions were either new or drastically changed. However, from that time on, they remained essentially the same until the fall of the Byzantine Empire in 1453.
Background history In the early Byzantine period (4th to late 6th century), the administrative structure of the empire was a conglomeration of the late Roman Empire's diocese system, set up by Diocletian and Constantine, and of Justinian's innovations; in the years 535 and 536 Justinian's administrative reforms were formalized. This eliminated the administrative diocese system hierarchy established in previous centuries and with it the strict military and civic divisions within the empire, replacing it with various provincial circumscriptions directly governed by deputies of the emperor, variously called Stratalates, Strategoi and Harmost. These deputies held extraordinary military and administrative powers accompanied by prestigious new titleholders in an attempt to lessen corruption and simplify the emperor's direct handling over its domains, foreshadowing similar future administrative reforms initiated and endorsed by contemporary divine Christian Orthodox monarchical philosophy in the Greek-speaking eastern Mediterranean.
Following the transformation of the Byzantine state during the 7th century due to massive territorial loss to the Muslim conquests, this early structuring came to be replaced by the thematic military system whose functions had been simplified and specialized in the rapid creation of provincial armies. Influenced by Christian Orthodox kingship and Hellenistic theocratic philosophies, power was relegated to military leaders, with the various Strategoi, Katepan, Douk, Kephalai or Exarch each acting as viceroys in their respective "thémata" or governorships, all being appointed by the sovereign directly. These governors, being the direct representatives of the monarch himself all through the provinces, enjoyed an omnipotence of their own, accompanied by the divine attributes for being deputies of the emperor himself in their respective districts. Their primary tasks were jointly working with the various provincial subordinates of the capital bureaus for the effective collection of taxes from the different communities ("Chora", "Komai"), from the different land owners estates ("proasteion"), and from monasteries ("episkepsis"). Additionally, and more commonly, as the right hand of the emperor in the management of internal and external affairs, they had to provide an efficient management of fast and flexible provincial armies, dispatching them to appease different threats within the borders, or for the management of new successful territorial acquisitions after long-term campaigns, thereby taking key roles as protagonists of any armed offensive headed by the emperor.
A Strategos, or any military governor, was assisted by several deputies, chief among them the tourmarchēs or merarchēs (to a lesser degree also referred as topotērētēs). The main provincial governors and their deputies held equal military and administrative duties within the main sub-division inside a thema, a tourma. These deputies, or any deputy or representative of the Strategos, or of any other military governor, were generally called Ek prosopou, second to them the Krites or Praitor were responsible for the judicial matters inside a Theme. Although the range of tasks of the Krites or Praitor were neither fixed nor dogmatic, as they are shown assisting in various military campaigns or, on occasions, replacing the Strategos in his military duties.
Due to the lack of action or large-scale battles in the thematas of mainland Greece, by the 12th century most of these came to be governed directly by the Megas doux, under him the Krites or Archons of the various coastal cities. The themes, now made up of several Archontates, was accommodated and repurposed solely for the income and maintenance of the Byzantine navy, fulfilling a tax supporting role in contrast from the more active and military themas of Strategos and Katepanos focussed in Asia Minor. The duties of said governors were limited to the collection of the various maritime taxes of their governorships; the management of the various urban centers such as Athens, Corinth or Thebes; and a basic level of protection for its provinces against pirates and any other parties.
During the "classic" or middle period of the Byzantine state (8th-late 11th centuries), a new, court-centered system emerged. In this, dignities of a certain level were awarded with new titles derived from older, now obsolete, public offices. A senatorial class remained in place, which incorporated a part of the upper officialdom; every official from the rank of protospatharios (literally "first sword-bearer"; originally the head of the Emperor's bodyguards) was considered a member of it. During this period, multiple families remained important for several centuries, and several Emperors rose from the aristocracy. Two groups can be distinguished: a metropolitan civil nobility and a provincial military one, the latter remaining regionally based and having land-holdings, but apparently no military forces of their own, in contrast to contemporary Western Europe.
The backbone of Byzantine administration and economy (until the fall of Constantinople) was the joint tax liability system of the different communities inside a théma, duties which were carried out by provincial officials such as the epoptes, exisotes, and praktores of the different bureaus. A Theme was made up of several individuals and institutions, such as the various lands that the monasteries owned (episkepsis), the soldiers' farming lands (stratiotai), the estates (proasteion) of the land owners (dynatoi) and the peasants (geōrgikē), with most of a village or town (chora or komai) being made up of the latter. These were the main source of a constant and rapid revenue that ultimately derived from the earlier Hellenistic fiscal and administrative principle of "epibole". Epibole had served as an accessible tool for the Hellenistic kingdoms for the simple income and rapid collection of taxes by deputies towards various rural communities in the war-time Hellenistic period, after having been adopted and adapted from the late Roman and early Byzantine province of Egypt, which had kept its own former fixed fiscal system, proving this measure to be an indirect consequence of the multiple wars and invasions that Byzantium had to deal throughout its history.