Short answers, pulled from the story.
In 1521, the Safavid Shah Ismail I sent an emissary to visit Czar Vasili III. This moment marked the official start of relations between the Grand Duchy of Moscow and the Persian Empire.
The Treaty of Gulistan in 1813 ceded modern-day Dagestan, Georgia, and large parts of Azerbaijan. The Treaty of Turkmenchay in 1828 resulted in the loss of Armenia and the remainder of Azerbaijan.
Russia became Iran's primary arms supplier between 2000 and 2007, accounting for approximately 85% of total military imports. Deliveries during this period were valued at $1.96 billion.
Russian president Dmitry Medvedev signed a decree banning further delivery of armored vehicles, warplanes, helicopters, and ships to Iran. This followed UN Security Council Resolution 1929 which imposed sanctions banning heavy weaponry sales.
On the 29th of September 2025, Iran signed a $25 billion agreement with Russia to build four small nuclear power plants in Sirik. These Generation III reactors are expected to produce 5 GW of electricity.