These powerful people from the stone age brought you your language. They were mobile but had as much technology as you needed. They arrived in Europe slightly after the first farmers.
According to Jones et al. (2015), Caucasus hunter-gatherers (CHG) "genomes significantly contributed to the Yamnaya steppe herders who migrated into Europe ~3,000 BCE, supporting a formative Caucasus influence on this important Early Bronze age culture. CHG left their imprint on modern populations from the Caucasus and also central and south Asia possibly marking the arrival of Indo-Aryan languages."