A large number of R1b-V1636 is found in Khvalynsk culture in Volga region (~4500bc). This is a from unpublished paper mention by Anthony. Other haplogroups found there are R1a, I2, Q, J1.
Khvalynsk is a copper age culture, usually considered the earliest pastoralist culture in Pontic Caspian Steppe. It was also the earliest culture in Steppe that had the Caucasian admixture, which later became the most recognizable feature of Yamna.
We have also one R1b-V1636 from ancient Arslantepe (Malatya). ~3000BC.
This V1636 was also found in Kur Arax culture from Kalavan, Armenia. 2600 bc.
Also two cases of V1636 were found in North Caucasian Steppic part called Piedmont. From Progress and Vonyuchka sites. 4300 BC. They were foragers.
Also we have new case of V1636 in ancient Danemark in a Single Grave Culture (~2500bc) which itself is a subgroup of Corded Ware. Corded Ware is an IE culture. And another possible case in Yamna.
So what is the directionality and origin?. Based on autosomes of Khvalynsk samples it is clear that V1636 herders moved to Volga region from South. Here there can be little doubt. V1636 was in most likelihood an early pastoralustic lineage. But from where it started it's journey?
One possibility is that V1636 learned pastoralism in the vicinity of North Caucasus from neighbouring farmers of Near Eastern origin. Later one branch moved to Volga region. While another branch moved to Near East reaching Arslantepe and maybe Anatolia.
It should be noted that this migration must have occured earlier than Kur Arax formed, thus earlier than 3600 BC.
Another possibility is that V1636 was present in South Caucasus since the Neolithic. It became part of local farmers communities and moved on its own to North reaching Volga region.
Additional ancient DNA is needed to solve this puzzle, which would be very important for understanding Yamna's origin.
V1636 is rare today. It can be found in few places like Armenia, Turkey, Italy, China also Volga region and in some Arabic countries.