Adding to the list of steppe empires, not an Asian one though, the Commanche Indians are way up there in terms of barbarism as well. Not just against the encroaching westerners, but other tribes as well. They really did not mess around with the sadistic torture of their war prisoners. Proper nightmare fuel.

There might be some form of selection bias by the OP? Neither the colonization of the Americas by various European "tribes", nor the brutal colonial empires in Africa in the 19th century seem to make the cut, and for some reason not even Nazi Germany is listed.

When it comes to the number of genocides, it is probably difficult to beat out the British, but they were always quite jolly about it, so I guess it wasn't that bad.

>It's interesting that 2/3 are central asian steppe empires/civilizations.

Google tells me the Timurids were Mongol descendents of Genghis Khan, so not really. 100% of that relevant data set is one extended family.

>What is it with that area and producing psychopathic tribes, not to mention being the origin point of several plagues.

The Mongols were little more "psychopathic" than many societies at the time, only distinctive in terms of their relative success, not their cruelty. Alexander the Great tortured and slaughtered people by the thousands, and Westerners don't consider him a barbarian or psychopath so much as a tactical genius and founder of the civilized world.