'Today few are aware that this part of the Turkish-speaking Caucasus in the past had a name other than Azerbaijan. Naming this region of the Caucasus 'Azerbaijan' led to the view that Azerbaijan is a country divided into two: one part in the north and the other half south of the Araxes River. First in the Caucasus and then later too in Iran, writers and poets began to elegise, yearn, and lament the 'division' of the country into two and soon expressions of 'Northern Azerbaijan' (i.e. the Turkic-speaking region of the Caucasus) and 'Southern Azerbaijan' (the real, historical Azerbaijan) began to appear. A number of Soviet historians and writers began using these false and misleading names in their books and articles to such an extent that our younger generation is now completely misinformed and unaware of the real facts and events.'' Iran's late Qajar period saw the major loss of territories in the northeast to Russia during the 19th century, including the region to the north of the Arax River historically known as Aran (Caucasian Albania) and later as Shirvan. In the upheavals that led to the establishment of the Soviet Union in the early 20th century, revolutionaries in Shirvan set up the Azerbaijan Democratic Republic in 1918, which later became the Republic of Azerbaijan. This adoption has continued to be a provocative one for the historical bearer of the name, the province of Azerbaijan in Iran. The prominent Iranian historian Enayatollah Reza (1920-2010) extensively researched the historical geography of Iran and the Caucasus. Here he provides a clear picture of the boundaries ancient and modern of the two territories of Azerbaijan to the south and Aran to the north of the Arax River. In the process he documents the advent of the Turks on the world stage and their migration into Azerbaijan, the Caucasus and Anatolia.