I don't think pre-modern conflicts can be framed under the modern concept of genocide very well. In any case the Mongols did not set out to obliterate specific

I don't think pre-modern conflicts can be framed under the modern concept of genocide very well. In any case the Mongols did not set out to obliterate specific groups because of ethnicity, race, religion, etc., per se. Maybe wanting tribute or territory is a stupid reason to obliterate a city, but it's not motivated by ethnic or racial animus. Similarly, revenge on an empire for the death of ambassadors that leads to the utter destruction and death of said empire's populace is maybe technically genocide under the "destroying a nation" framing, but it doesn't fit into the modern cultural framing of nations in a nationalistic cultural sense, and would be considered a traditional casus belli. In any case I don't deny that they were rapacious, violent, expansive, or killed disproportionate numbers of people and reduced populated (for the time period) empires to grassland. But it was all very practical, not based on hate, and is totally in line with what other empires and civilizations would do in the time period if they had the means.