The Georgian kingdoms were contested between the Sasanids and the neighboring rivalling
Roman-
Byzantine Empire ever since the 3rd century. Over the span of the next hundreds of years, both the Byzantines and the Sasanids managed to establish hegemony over these regions. At the few remaining times, the Georgian kings managed to retain their autonomy. Sasanian governance was established for the first time early on in the Sasanian era, during the reign of King
Shapur I (r. 240-270). In 284, the Sasanians secured the Iberian throne for an
Iranian prince from the
House of Mihran, subsequently known by his dynastic name
Mirian III. Mirian III became thus the first head of this branch of the Mihranid family in the Kingdom of Iberia, known as the
Chosroid dynasty (otherwise known as the Iberian Mihranids, or Mihranids of Iberia), whose members would rule Iberia into the sixth century. In 363, Sasanian suzerainty was restored by king
Shapur II (r. 309-379) when he invaded Iberia and installed
Aspacures II as his vassal on the Iberian throne. The continuing rivalry between Byzantium and Sasanian Persia for supremacy in the
Caucasus, and the unsuccessful insurrection (523) of the Georgians under Gurgen had severe consequences for the country. Thereafter, the king of Iberia had only nominal power, while the country was effectively ruled by the Persians. By the time of
Vezhan Buzmihr's tenure as
marzban of Iberia, the
hagiographies of the period implied that the "kings" in
Tbilisi had only the status of
mamasakhlisi, which means "head of the (royal) house". When
Bakur III died in 580, the Sassanid government of Persia under
Hormizd IV (578-590) seized on the opportunity to abolish the Iberian monarchy. Iberia became a Persian province, administrated through its direct rule by appointed
marzbans, which in fact was, as Prof.
Donald Rayfield states; "a
de jure continuation of
de facto abolition of Iberian kingship since the 520s". The Iberian nobles acquiesced to this change without resistance, while the heirs of the royal house withdrew to their highland fortresses – the main
Chosroid line in
Kakheti, and the younger
Guaramid branch in
Klarjeti and
Javakheti. However, the direct Persian control brought about heavy taxation and an energetic promotion of
Zoroastrianism in a largely
Christian country. Therefore, when the
Eastern Roman emperor Maurice embarked upon a
military campaign against Persia in 582, the Iberian nobles requested that he helped restore the monarchy. Maurice did respond, and, in 588, sent his protégé,
Guaram I of the Guaramids, as a new ruler to Iberia. However, Guaram was not crowned as king, but recognized as a presiding prince and bestowed with the
Eastern Roman title of
curopalates. The Byzantine-Sassanid treaty of 591 confirmed this new rearrangement, but left Iberia divided into Roman- and Sassanid-dominated parts at the town of
Tbilisi.
Mtskheta came to be under Byzantine control. Guaram's successor, the second presiding prince
Stephen I (Stephanoz I), reoriented his politics towards Persia in a quest to reunite a divided Iberia, a goal he seems to have accomplished, but this cost him his life when the Byzantine emperor
Heraclius attacked Tbilisi in 626, during the
Byzantine–Sasanian War of 602–628, marking the definite Byzantine predominance in most of Georgia by 627-628 at the expense of the Sasanids until the
Muslim conquest of Persia. ==Protection, construction activities and settlers==