Relations between the Grand Duchy of Moscow and the Persian Empire (Iran) officially commenced in 1521, with the Safavids in power. Past and present contact between Russia and Iran have long been complicatedly multi-faceted; often wavering between collaboration and rivalry. The two nations have a long history of geographic, economic, and socio-political interaction. Mutual relations have often been turbulent, and dormant at other times. The Russian Empire had an oppressive role in Iran during the 19th and early 20th centuries which harmed Iran's development, and during most of the ensuing Soviet period, the shadow of the "big northern neighbour" continued to impend. Since the fall of the Soviet Union, the two neighboring nations have generally enjoyed very close cordial relations. Iran and Russia are strategic allies and form an axis in the Caucasus alongside Armenia. Iran and Russia are also military allies in the conflicts in Syria and Iraq and partners in Afghanistan and post-Soviet Central Asia; and shares a common interest in suppressing Sunni Islamism and pan-Sunni political groups. The Russian Federation is also the chief supplier of arms and weaponry to Iran. Due to Western economic sanctions on Iran, Russia has become a key trading partner, especially in regard to the former's excess oil reserves. Currently Russia and Iran share a close economic and military alliance, and both countries are subject to heavy sanctions by most Western nations. Militarily, Iran is the only country in Western Asia that has been invited (in 2007) to join the Collective Security Treaty Organization, the Russia-based international treaty organization that parallels NATO. As soon as he became president, Vladimir Putin pursued close friendship with Iran and deepened Russian military cooperation with Iran and Syria. In 2015, Putin ordered a military intervention in Syria, supporting the Assad regime and its Iranian allies with an aerial bombing campaign against the Syrian opposition. While much of the Iranian military uses Iranian-manufactured weapons and domestic hardware, Iran still purchases some weapons systems from Russia. In turn, Iran assisted Russia with its drone technology and other military technology during its invasion of Ukraine. Iran has its embassy in Moscow and consulates in the cities of Astrakhan and Kazan. Russia has its embassy in Tehran, and consulates in Rasht and Isfahan. History Russian Empire Pre-Safavid era Contacts between Russians and Persians have a long history, extending back more than a millennium. There were known commercial exchanges as early