Short answers, pulled from the story.
Formal diplomatic relations between Iran (then Persia) and Russia (then the Grand Duchy of Muscovy) began in 1521, when Safavid Shah Ismail I sent an emissary to Grand Prince Vasili III. The two countries exchanged ambassadors for the first time in 1552-53 and established a regular diplomatic relationship starting in 1586.
Russia took vast Iranian territories through two treaties in the 19th century. The Treaty of Gulistan in 1813 ceded what is now Dagestan, Georgia, and large parts of the Republic of Azerbaijan. The Treaty of Turkmenchay in 1828 added modern-day Armenia and the remainder of the Azerbaijan Republic. All the lands north of the Aras River, including parts of today's Georgia, Azerbaijan, Armenia, and Dagestan, were Iranian until Russian conquest.
Khomeini used the term "Lesser Satan" for the Soviet Union because of its atheistic communist ideology, which he deemed fundamentally incompatible with Islam. He rejected alignment with either the United States or the USSR during the Cold War, though he reserved the title "Great Satan" for the United States.
Iran supplied Russia with Shahed-136 loitering munitions under a reported agreement worth $1.75 billion, which included both drone deliveries and technical assistance for domestic production inside Russia. By 2025, a manufacturing facility in the Alabuga Special Economic Zone in Tatarstan had localized the majority of drone production, reducing reliance on Iranian components.
The Iranian-Russian Treaty on Comprehensive Strategic Partnership was signed on the 17th of January, 2025, by Vladimir Putin and Iranian president Masoud Pezeshkian. It covers politics, security, trade, transport, and energy. The treaty explicitly does not constitute a military alliance and does not commit Russia to defend Iran.
Trade between Iran and Russia rose 81% to a record $3.3 billion in 2021. By 2022-23, Russia was Iran's largest investor at $2.7 billion. Major Iranian non-oil exports to Russia include motor vehicles, fruits, vegetables, textiles, hand-woven carpets, and plastics, while Russia supplies Iran with arms, nuclear technology, and basic agricultural goods such as wheat, barley, and vegetable oil.