Alternate worlds where the Indo European Expansions didn't happen.
A plausible POD would be the Neolithic Decline not happening.
The Yamnaya could survive as rulers of the region of Ukraine and the Russian Steppe, but don't spread out from there.
The changes would be massive.
India would not be taken over by the Vedic peoples.
The Persian and Roman Empires would never exist, completely changing the course of history and religion.
Europe would be totally different. Imagine the ways the Cucuteni Trypallians, or the Megalith builders could have advanced in time where they survived.
Even east Asia could be totally different, without the nomadic Iranian peoples influencing them we might not have had any Xiongnu, Mongols, or the like.