Afanasievo (pre-proto-Toharians) in the Upper Yenisei - closely related to the Yamnaya people of the West. 
Afanasievo (& Toharians) split off from the main branch of Indo-Europeans (Germanic, Italo-Celtic, Indo-Iranian, etc) at some point between 3700 and 3300 BC. This pre-proto-Toharian branch possibly included the lost Indo-Europeans of modern-day Udmurtia & Kirov Oblast.
Afanasievo people expanded as far as central Mongolia, but faded away in Mongolia by mid third millennium BC. They left little ancestry in their successors in the region.
Afanasievo in Altai & Dzungaria (area surrounding modern Urumqi in Xinjiang) was succeeded another Indo-European group (Chemurchek Culture ru.wikipedia.org/wiki/%D0%A7%D0…) who almost completely replaced them. Like Afanasievo, Chermurchek were milk drinkers.
The Chemurchek proved as transient as the as Afanasievo. The locals adopted their milk drinking habits & other parts of their culture.. The Chemurchek left little genetic trace, so were either a small minority that was absorbed or were destroyed.
Formation of a "North Mongolia" race - 80% from modern groups like Nivkhs & Tungustics (abbreviated "ANA) who used to rule an arc from Amur to Baikal, 20% from "Ancestral North Eurasians" (abbreviated "ANE") from south Siberia (southern Krasnosyarsk Kray & Irkutsk Oblast)
The ANE had been marching east in the 4th millennium BC - the "North Mongol" race had 3x as much ANE ancestry by the Early Bronze Age (3rd millennium) as it had in the Eneolithic (Copper) Age (4th & 5th millennia)
Climate change in 2nd millennium BC led to expansion of grasslands of Eurasia. Horse use and horse milking expanded widely, possibly introducing alcohol to the steppe.
Corded Ware people riding east became the Sintashta Culture, the earliest Indo-Iranians. Some of them made it to W Mongolia, where they mixed with the locals in mid-to-late 2nd millennium BC. Orange in the pie charts in Sintashta-associated ancestry.
Some weird evidence for some part-Toharian groups surviving in Mongolia into mid 2nd millennium BC, as well as possible contact with BMAC independent of Iranians. Seems like something else is going on.
The Saka expanded out of what is now Uzbekistan in the early 1st millennium BC. They were another Iranian group, mixed with their fellow Iranians who had lived in W Mongolia for a few centuries by that point.
Orange is Corded Ware/Sintashta-like ancestry, brown is Zagros Farmer-like ancestry, cyan is the ANA-ANE mix described earlier in the thread.
E Mongolia remained dominated by pure ANA people from 4600 BC well into the 1st millennium BC, when they began pushing the "North Mongols" out of E Baikal area. Green in the ANA component in the pie charts of Copper to Iron Ages in Mongolia.
Xiongnu (possibly related to Huns) were the first recorded large steppe empire, and ruled much of Central Asia & Mongolia from the 3rd century BC to the first century AD.
Iranians kept migrating east into Mongolia through the first half of the 1st millennium BC. With the rise of the Xiongnu in 2nd half of the millennium, the peoples of W & E Mongolia began to merge together - in blood as much as politics.
The Xiongnu married Chinese princesses & recruited Chinese to join their armies. They also drew Sarmatians from the western steppe into their realm. Sarmatians & Chinese appear in later Xiongnu samples. They were absorbed into the general Xiongnu population.
Xiongnu collapsed around 100 AD. The ensuing realms in Mongolia were quite different - ranging from a pure Iranian group (more Saka?) to pure ANA - (Turks or Uyghurs). Also evidence of enslavement of Chinese & human sacrifice.
Uyghurs were very heterogeneous even in the 6th century AD - some were more than half Iranian, others almost pure ANA.
Khitans were almost entirely East Asian in ancestry, with the paper's model showing a Han-like component comprising a larger fraction of their ancestry than the ANA-like component. Wonder if due to origins as a prehistoric Han splinter group, or more recent mixing.
Mongols of the Genghis Khan's time were ~15% "Sarmatian", ~60% ANA, & ~25% Han. The "North Mongolia" race (~80% ANA & 20% ANE mix) discussed earlier in this thread contributed little, if any, ancestry to them.
Modern Mongols are mostly descendants of the Mongols of Genghis Khan's time. Y chromosomal haplogroup C2b is found in a third of Mongols, and was presumably the line of Genghis Khan himself.
You can read the paper here: biorxiv.org/content/10.110…
@Pozzidonius1 @espressosoldo @tocharianstan @June_beetle @Mirza_Mirza00 @samanrtmwrt @BaruchKogan @Bollocksworth @SkanderbeuMK3 @backonmybupkis @Landedpaisa @whyvert @qin_duke @SurvivetheJive thread with excerpts on the recent Eastern Steppe DNA paper you might be interested in
