During the twentieth century, the socialist bloc became a second home for socialists from Iran and Afghanistan. Iranian socialists almost certainly constituted the largest foreign diaspora in the USSR at the time of its dissolution, and Soviet entanglements in Afghanistan led to a large flow of Afghan soldiers, students, and socialists to the Soviet Union in the latter half of the twentieth century. The USSR also sponsored Persian socialist internationalism domestically in the form of the Tajik SSR. This paper uses sources from all three sides of the “Persianate triangle” (Tajikistan, Iran, and Afghanistan) to highlight how encounters between socialist groups often highlighted differences between these groups' understanding of socialism despite a shared Persian language. More broadly, it points to the importance of “subnational actors” in the making of Soviet foreign policy. Case studies of a Tajik translator in the Democratic Republic of Afghanistan as well as Iranian socialist exiles in Kabul also show how the memory of socialist internationalism has been processed and narrated very differently within the Iranian diaspora and Tajikistan today. In conclusion, the article shows how the networks forged by Soviet internationalism have often been reworked in the wake of the collapse of the USSR and offers reflections on how scholars can engage further in the study of “subnational internationalism.”