For the most part the Mongols conquered territory for the purpose of taxing it or opening it up to trade. The local Mongol populations ended up being quite tiny. Eastern Europeans, as a whole, have no more Eastasian ancestry than Western Europeans and that's mostly from events during the Ice Age.
The big killings were done further South in the Islamic countries where, frankly, none of us care how many Moslems they killed nor what they did with the land.
The only reason the Mongols didn’t slaughter more Europeans is because the big Mongol warlord, Ogedei or Ogotai, croaked during the campaign to invade Austria and they all returned to Mongolia.