The Roman Empire controlled Caucasian Albania only as a vassal state, never fully incorporating it as it temporarily did with neighboring Armenia. This influence started in the first century BCE and lasted until around 250 CE. But around 299 CE Albania was again briefly a Roman vassal state under Emperor Diocletian.
Indeed, in 65 BC the Roman general Pompey, who had just subjugated Armenia and Iberia and had conquered Colchis, entered Caucasian Albania at the head of his army. He clashed with the forces of Oroezes, king of Albania, and quickly defeated them. Pompey ensured the control of Albanians nearly reaching the Caspian sea before returning to Anatolia.
But the Albanians, influenced by the Parthian Empire were not slow to revolt against Rome: in 36 BC Mark Antony found himself obliged to send one of his lieutenants to bring an end to their rebellion. Zober, who was then king of Albania, capitulated and Albania thus became -at least in name- a "Roman protectorate", starting a condition of vassalage that lasted for nearly three centuries.
In 35 AD King Pharasmanes of Iberia and his brother Mithridates, with the support of Rome, confronted the Parthians in Armenia: the Albanians proved effective allies, contributing to the defeat and temporary eviction of the Parthians.
Emperor Nero prepared in 67 AD a military expedition in the Caucasus: he wanted to defeat the barbarian Alans and conquer for Rome all the northern shores of the Black sea from actual Georgia-Azerbaijan to what is now Romania-Moldavia, but his death stopped it.
Successively Vespasian was determined to restore and reinforce the full authority of Rome in the Caucasus as far as the Caspian sea. He probably founded a Roman town called "Laso", recently rediscovered inside the actual city of Ganja.
Despite the growth of Roman influence, Albania never ceased to remain in commercial, ethnical, and cultural contact with Persia, but with Trajan in 114 AD Roman control over Caucasian Albania was nearly complete with top social levels fully romanized.
The Princes also of the Caucasian tribes, the Albani, the Iberi....even those of the trans-Caucasian Sarmatae were confirmed in the relation of (Roman) vassallage or now subjected to it (by Trajan)
This invasion promoted an alliance between Rome and the Albanians that was reinforced under Antoninus Pius in 140 AD. Sassanians occupied the area around 240 Ad but after a few years the Roman Empire regained control of Caucasian Albania.
Indeed, in 297 AD the Treaty of Nisibis stipulated the reestablishment of the Roman protectorate over Caucasian Iberia and Caucasian Albania. But fifty years later Rome lost the area that since then remained an integral part of the Sassanian Empire for more than two centuries.
In the late sixth century the territory of Albania became again an arena of wars between Sassanian Persia and the Byzantine/Eastern Roman Empire. During the third Perso-Turkic War, the Khazars (Gokturks) invaded Albania, and their leader Ziebel declared himself Lord of Albania in 627 AD under the Roman Heraclius rule, levying a tax on merchants and the fishermen of the Kura and Araxes rivers, which was "in accordance with the land survey of the kingdom of Persia". The Albanian kings retained their rule by paying tribute to the regional powers.
The presence of a detachment of the Legio XII Fulminata at a distance of some kilometers from the shores of the Caspian sea, in Gobustan National Park, near Qobustan (69 km south of Baku) is attested by an inscription drawn up between 83 and 96 AD in the reign of Domitian. This is one of the most eastern places reached by Roman legions.
In 75 AD, XII Fulminata was in Caucasus, where Emperor Vespasian had sent the legion to support the allied kingdoms of Iberia and Albania.
Indeed, in Azerbaijan, an inscription has been found which reads: IMP DOMITIANO CAESARE AVG GERMANICO LVCIVS IVLIVS MAXIMVS LEGIONIS XII FVL, Under imperator Domitian, Caesar, Augustus Germanicus, Lucius Julius Maximus, Legio XII Fulminata.
Some historians argue that the actual settlement of Ramana near Baku was possibly founded by the Roman troops of Lucius Julius Maximus from "Legio XII Fulminata" in the first century AD and derives its name from the Latin Romana.
Among the facts that strengthen this hypothesis are the military-topoghraphical map of Caucasus published in 1903 by Russian Administration which spells name of town as "Romana", various Roman artefacts found in the Absheron region and also old inhabitants' referring to the town as Romani.
Additionally, Ramana is positioned in an area perfectly suited for a Roman "castrum" to control nearby Baku' s port, on the commercial sea route (through the Caspian sea) between the Caucasus and the Central Asia plains.[original research?]
Christianity started to enter Caucasian Albania, according to Movses Kaghankatvatsi, as early as during the 1st century, exactly when Romans imposed their initial control on Albania. The first Christian church in the region[unreliable source] was built by St. Eliseus, a disciple of Thaddeus of Edessa, at a place called Gis and is believed to be the modern-day "Church of Kish".
After Armenia adopted Christianity as its state religion (301 AD), the Caucasian Albanian king Urnayr went to the See of the Armenian Apostolic Church to receive baptism from St. Gregory the Illuminator, the first "Patriarch of Armenia".
Christianity reached its golden age in the late fifth century under Vachagan the Pious (ruled 487–510 AD), who launched a campaign - influenced by Byzantine priests - against idol worship in Caucasian Albania and discouraged Persian Zoroastrianism.
After the Muslim invasions of the seventh century the original Christians have nearly disappeared from actual Azerbaijan. However, Church of Kish - founded by the apostle Eliseus in Sheki, as well as the monasteries Gandzasar, Targmanchats and Amaras in Karabagh have reached our times in relative good shape.
This Arab conquest led to severe disintegration of the Church of Caucasian Albania. Starting from the 8th century, much of the local population underwent mass Islamization. By the 11th century there already were conciliar mosques in Partaw, Qabala and Shaki: the cities that were the creed of Caucasian Albanian Christianity. These Islamised groups would later be known as Lezgins and Tsakhurs or mix with the Turkic and Iranian population to form present-day Azeris, whereas those that remained Christian were gradually absorbed by Armenians or continued to exist on their own and be known as the Udi people.
Actually the only remaining Caucasian Albanians are the Udi people, who maintain the Christian faith. Indeed, when Russia took possession of the region of actual Azerbaijan, the village of Kish had Udi population and, according to Robert H. Hewsen, the Udi language appeared to have been prevalent north of the Kura River until the nineteenth century.