Wang et al. (2018) discovered that this middle Volgamating network extended down to the North Caucasiansteppes, where at cemeteries such as Progress-2 andVonyuchka, dated 4300 BC, the same Khvalynsk-type ancestryappeared, an admixture of CHG and EHG with no AnatolianFarmer ancestry, with steppe-derived Y-chromosomehaplogroup R1b. These three individuals in the North Caucasussteppes had higher proportions of CHG, overlapping Yamnaya.Without any doubt, a CHG population that was not admixedwith Anatolian Farmers mated with EHG populations in theVolga steppes and in the North Caucasus steppes before 4500BC. We can refer to this admixture as pre-Yamnaya, because itmakes the best currently known genetic ancestor for EHG/CHGR1b Yamnaya genomes. The Progress-2 individuals from NorthCaucasus steppe graves lived not far from the pre-Maikopfarmers of the Belaya valley, but they did not exchange mates,according to their DNA.The hunter-fisher camps that first appeared on the lowerVolga around 6200 BC could represent the migration northwardof un-admixed CHG hunter-fishers from the steppe parts of thesoutheastern Caucasus, a speculation that awaits confirmationfrom aDNA. After 5000 BC domesticated animals appeared inthese same sites in the lower Volga, and in new ones, and ingrave sacrifices at Khvalynsk and Ekaterinovka. CHG genes anddomesticated animals flowed north up the Volga, and EHGgenes flowed south into the North Caucasus steppes, and thetwo components became admixed. After approximately 4500 BCthe Khvalynsk archaeological culture united the lower andmiddle Volga archaeological sites into one variablearchaeological culture that kept domesticated sheep, goats, andcattle (and possibly horses). In my estimation, Khvalynsk mightrepresent the oldest phase of PIE.