Azerbaijan naming controversy

The toponym "Azerbaijan" has been the object of a naming controversy since 1918 between the region of Azerbaijan in Iran and the Republic of Azerbaijan in the South Caucasus. The toponym historically belongs to the former, i.e. the region of Azerbaijan in northwestern Iran, south of the Aras River, while historians and geographers usually referred to the region north of the Aras River as Arran, even though the name "Azerbaijan" had also sometimes been extended to this area as well (see § Extension to the north of the Aras). On May 28, 1918, following the collapse of the Russian Empire, the Azerbaijan Democratic Republic was proclaimed to the north of the Aras, triggering the controversy.