Eastern Armenia, thereafter known as Russian or Transcaucasian Armenia

Восточная Армения — Араратская долина с прилегающими к ней горными областями Малого Кавказа (Лори, Иджеван, Зангезур и др.) — была центром формирования армянской нации.

Their activity centered on various towns in eastern Armenia, of which Julfa was the most prominent

«At the time, much of the focus was on the heartland of Turkish Armenia, but two regions in Transcaucasian Armenia also stirred significant irredentist feelings: Nagorno-Karabakh and Nakhichevan—both of which were attached to Azerbaijan under the imperial Russian system of administration.»

With the exception of the period of Arabic influence over Armenia during the Caliphate (7th-9th centuries A.D.), this Persian power extended from the time Darius the Great until the early 19th century, when the Russian Empire took over the control of Caucasian Armenia and, increasingly under the Soviet period ….

The province of Nakhichevan, which forms the south-eastern part of Russian Armenia, is divided into two districts— Nakhichevan and Ordoobad

In present-day terms, historic Armenia comprised a large parts of eastern Turkey, the northeastern corner of Iran, parts of the Azerbaijan and Georgian republics, as well as the entire territory of the Armenian Republic. It was defined by a number of natural boundaries: the Kura River, separating the Armenian highlands from Caspian and Georgian lowlands in the east and northeast; the Taurus-Zagros chains, connecting to the Iranian Plateau and separating Armenia from Kurdistan and Iran in the south and southwest, and Euphrates River, marking and western boundary of historic Armenia

Historic or Greater Armenia includes not only the Republic of Armenia but also a small area in northeastern Iran, most of the eastern part of Turkey, and secitions of the present republics of Azerbaijan and Georgia

At the start of the sixteenth century, Armenia became the center of conflict between the Ottoman sultans and the Safavid shahs of Persia. After continuous warfare between the two empires, a compromise was finally leached by the Treaty of Zuhab in 1639. Under this agreement, the Ottomans recognized almost all of Transcaucasia as being part of Persia. The plain of Shuragial and the Arpachai River became a sort of boundary; Armenian lands east of that zone were considered part of Persia, and all lands west of it fell into the Ottoman sphere. The terms "Eastern" or "Persian" Armenia and 'Turkish" or "Western" Armenia were soon coined by contemporary travelers, geographers, and historians.
For the next eight decades Eastern Armenia remained under the control of the Safavids, who divided it into two administrative units: Chukhur-i Sa'ad, or the territory of Erevan and Nakhichevan; and Karabagh, formed from the combined regions of Karabagh, Zangezur (Siunik) and Ganja.

«Hence by the second haf of the eighteenth century, Eastern Armena was composed of four khanates: Erevan, Nakhichevan (which included a number of settlements south of Araxes River), Karabakh (which included Zangezur), and Ganja.»

«The Republic of Armenia comprises the north-eastern part of the historic kingdom of Armenia»

Importantly, disunion amongst the five princes allowed the establishment of a foothold in mountainous Karabakh by a Turkic tribe around 1750. This event marked the first time that Turks were able to penetrate the eastern Armenian highlands…»

Only pockets such as Karabagh (Karabakh) and Zangezur in eastern Armenia and Sasun and Zeitun in western Armenia remained autonomous

After repeated rebellions, independence, and reconquest, the last of the Armenian kingdom was conquered by the Arab Mamelukes in 1375. The only reamaining autonomous pockets of Armenian were in Karabakh and Zangezour, bothe in eastern Armenia

Иран вынужден был заключить с Византией договор о дружбе и уступить ей часть Картли до Тбилиси и часть Восточной Армении до озера Ван. На освобождённой от персов части Картли утвердился местный князь. В Албании в конце VI в. возродилась местная государственность во главе с наследственным князем. В оставшихся под властью Ирана частях Картли и Армении иранское правительство также должно было пойти на значительные уступки местной знати. Но положение крестьянства оставалось по-прежнему тяжёлым. После победы Византии над сасанидским Ираном (628 г.) его владычество в странах Закавказья фактически пало, хотя и власть Византии являлась там лишь номинальной.

Having seized Artasires, he deposed him and united his dominions with Persia (A.D. 428). Eastern Armenia was then called Persarmenia

After the Byzantine-Persian partition of Armenia in A.D. 591, the emperor Maurice organized his newly acquired territories in east central Armenia into a Byzantine province, which, probably from its elevation relative to the rest of Armenia, was designated Lower Armenia (Armenia Inferior).

Armenian dignitaries moved to Byzantium again after the second partition of Armenia in 591

As the Byzantine frontier moved eastward after the partition of the Armenian Kingdom ca. 387 and again 591, these norms were apparently extended to the newly annexed territories

Nine of these territories were lost in 387, most of them forever; there others — Vaspurakan, Turuberan, and Tayk — emerged only after the Byzantine-Persian partition of Armenia in 591, when the districts of which they were comprised passed under Byzantine control»

591
In the partition of Armenia between Perisa and Byzantium, most Armenian territory becomes a dependency of Eastern Rome

During the almost 250 years of Arab rule in Armenia (7th-9th cents.), the Bagratids gradually assumed the paramount position among the surviving Armenian princes and ca. 884 were able to establish a new monarchy in central Armenia which included all of Lower Armenia and considerably more territory in eastern Armenia as well.