High Quality Content by WIKIPEDIA articles! The Russo-Persian Treaty of Friendship was signed on February 26, 1921 between representatives of Iran and the Soviet Russia. Based on the terms of the treaty, all previous agreements made between the signatories including the Treaty of Turkmenchay were canceled. Moreover, both the Soviet Russia and Iran were given full and equal shipping rights in the Caspian Sea along with the right to fly their respective national flags on their commercial vessels. Ratifications were exchanged in Teheran on February 26, 1922. It was registered in League of Nations Treaty Series on June 7, 1922. The original purpose of the treaty was to prevent White Russian counter-revolutionary forces who fled to Iran after the Bolshevik Revolution, from attacking the Soviets from Iranian territory. The Soviets however would use it to menace the Iranians for years to come.