For five years, a group of nationalist guerrilla fighters and communists had roamed the forests of Gilan, an Iranian province curving around the southwestern shore of the Caspian Sea. On June 4, 1920, they entered the regional capital Rasht, proclaiming the Soviet Socialist Republic of Iran (SSRI).

“Now this national force,” they told the inhabitants, who welcomed them as liberators, “with the help and assistance of all the humanitarians of the world and with the perseverance of just principles of socialism . . . has entered the stage of the Red Revolution.”

The revolution, they believed, wasn’t to be limited to Gilan — rather, it would challenge British imperialism and Iran’s collaborationist ruling class in the national capital, Tehran. And indeed for sixteen months, the red flag flew over the region, also casting a shadow over the rest of the country. Yet by October 1921, the central government troops, aided by the British, had managed to quell the Gilan rebellion, and Soviet Russia withdrew its support. These events paved the way for the autocrat Reza Khan, who had earlier that year risen to power through a coup in Tehran; this was the context in which he established the Pahlavi monarchy, which would endure until 1979.