ABSTRACT With an origin in western Eurasia, the Indo-Iranian languages appeared in Greater Iran and beyond in the second millennium and were expressed widely in the first millennium BCE. Considering an early separation of Proto-Iranian from the Proto-Indo-Iranian linguistic core, Eurasian archaeological cultures affiliated with Indo-Iranians are revisited. While the Sintashta and Petrovka cultures, along with the Alakul Andronovo cultural complex, are plausible reflections of the Proto-Indo-Aryans, the situation is more complex for the Proto-Iranians who later shaped the cultures of the Scythians and Iranians of Greater Iran. Tracing the origins of these Proto-Iranians in the Inner Asian Mountain Corridor and Central Asia, their possible expansion into Greater Iran, partly separated from the Proto-Indo-Aryan path, is demonstrated. An Iranian-speaking group in Transoxiana, distinct from the Iranians of Greater Iran, is also discussed with the Proto-Iranian affiliated Timber Grave culture of western Eurasia as one of its possible components.