I suspect that the reindeer herder would come to dominate the mammoth steppes primarily, while they would herd their reindeer, they would also stay big game hunters beside being hunters, but the greater mobility and transportation capacity would allow bigger populations and a more complex tool kit. the higher mobility and bigger population enable them to develop a trade network, which increase their sophistication. All in all thos in short term enable them to upkeep a higher population density one more similar to the hunter gatherers in the more fertile regions further south. But they don’t move south as the reindeer do badly in the hotter climate. But over time we see the development of semi-sedentary settlements. These are first the rare annual market, but later we see settlement focusing on flint and salt mines, salt enable them to make better use of fishing resulting in a few permanent fishing hamlets whose goods enter the herder trading network, but also increases in tool complexity as we first see the first copper mines and later tin mines. The herders enter a long Bronze Age, increased complexity from that point are improvement in tool kit, move to a riding culture, but fundamental they’re limited by a smallish population and inability to move south, we see some movement into arctic deserts of East Asia and the dry lands north of the North American glaciers.
Many of the megafauna likely survives as the get used to be hunted more active. So the mammoth and wholly rhino survives on the Great Eurasian steppes as the Ice Age end. Of course for the herder it’s more dramatic, their trade networks doesn’t collapse, but they see a major disruption. We may see a move away from bronze and to iron, as it’s easy to get. As such humanity enter the post-Ice Age world as a iron using culture.
