Arran (Caucasus)

Arrān (Middle Persian form; New Persian: اران) is an Iranian toponym which in ancient times referred to the country of Caucasian Albania, which was originally located north of the Kura River but later expanded to territories south of the river as well. In the post-Islamic period, Arran came to signify only the region which lay within the triangle of land, lowland in the east and mountainous in the west, formed by the junction of the Kura and Aras rivers.

The Caucasian Albanian kingdom, which emerged in the 1st century BC, was subject to Sasanian Iran from the 3rd century AD. After 387, Albania expanded its territory across the Kura at Armenia's expense, now encompassing a territory roughly corresponding to that of the modern-day Republic of Azerbaijan. The Sasanians abolished the local monarchy c. 510 AD. After the Islamic conquests, the local princes of Albania continued their existence under caliphal authority, although they became increasingly fragmented over time. Independent Muslim emirates emerged along the Caspian coast after the waning of caliphal power in 9th century; but these did not claim Arran in their titles, and the term Arran came to designate the smaller area between the Kura and Aras rivers.

Albania converted to Christianity between the early 4th and early 5th centuries. Islam spread to the region after the Islamic conquests; the eastern lands of Albania, along the Caspian, appear to have converted earlier, corresponding to the shift of the definition of Albania/Arran in the 10th century. Christians still formed a majority in Arran in the 10th century. The process of Islamization was completed by the Turkic and Mongol invasions in the 11th–13th centuries; this was accompanied by the region's Turkification. The population of Arran which remained Christian was ultimately absorbed by the Armenians and in part by the Georgians; north of the Kura, in historical Caucasian Albania proper, the Udi people maintained their Christian faith and a language which is either directly descended from or closely related to the Caucasian Albanian language. The term Arran had fallen out of common use by the 15th century; the region was associated with Azerbaijan, and the land between the Kura and Aras rivers came to be known as Karabakh.

Today, the term Aran is mainly used in Azerbaijan to indicate territories consisting of Mil and Mughan plains (mostly, Beylagan, Imishli, Kurdamir, Saatly, Sabirabad provinces of the Republic of Azerbaijan). It has also been used by Iranian historian Enayatollah Reza to refer to the country of Azerbaijan, freeing the name "Azerbaijan" to refer to a region within Iran.