Data suggests a decline or collapse of Yamnayan populations in the Central Steppe during the late third millennium BC, and its replacement by (for want of a better expression) Indo-Aryan types, approximately as below:
Samara 3,000 BC -100% Yamnayan
to Poltavka 2,400 BC - 60% Yamnayan
to Potapovka 2,200 BC - 30% Yamnayan
to Sintashta 2,000 BC - 1% Yamnayan

Does anyone have any data or other information/suggestions about this?