It was only a few weeks ago that Russian President Vladimir V. Putin and Iranian President Masoud Pezeshkian met to ink the historic Russo-Iranian Treaty on Comprehensive Strategic Partnership. The pact itself was a milestone, so much so that commentators around the world are still widely discussing its implications. Perhaps one of the most striking elements of the treaty is the major focus on Eurasia. Although Western analysts tend to focus on Russo-Iranian cooperation in the Middle East, the treaty indicates that Eurasia is of even more immediate geopolitical significance to both Moscow and Tehran. To historians and long-time observers of Iran and Russia, this is hardly a surprise. The Eurasian region – that is, the Caucasus, Central Asia, and the Caspian Sea – forms an integral part of the common Russo-Iranian neighborhood.