

Also, the Mongols.
The Kievan Rus was geographically unfortunate enough to stand in between the Mongol invasion and the rest of Europe in the 13th century, and the Russian/Eastern Slavic people spent the next four centuries on a stalemate with the descendants of the Mongols (Tatars), became the victims and captured slaves of frequent Tatar raids that went on for centuries, while effectively shielding the European subcontinent from total destruction.
Edit: obviously the Islamic civilizations were destroyed during the Mongol invasion and China itself suffered from both an external invasion and internal political upheaval until the Ming dynasty in the 15th century.
This is going to shock some people, but Putin is not a mass murderer.
Unlike NATO which destroyed every critical infrastructure (energy, water etc.) during the invasion of Iraq and Libya and condemned millions to death and destruction, the Russian invasion of Ukraine has shown magnitudes of order of restraint, repeatedly, even to the detriment of its own military campaign (of course, there is also a propaganda component at play here).
In fact, Russia only steps up its strikes on energy infrastructure as responses in kind, when their opponents first had initiated a provocation. This also happens on the economic front, where their sanctions on gas delivery was made in response to the Europeans violating the contractual agreements first. This is why you’d never see a lawsuit against Russia turning off the gas flow where the court ruling favors the European party.
Russia wants to punish NATO, but not the European people, just like it wants to punish the Banderite Nazis, not the Ukrainian people.
Collapsing Europe also wouldn’t end the war, it would create a chaotic and disastrous political situation right next to its border in ways that nobody could predict (nobody wants to plunge the world into another world war again).
Remember, Putin is a soft-hearted lib and has demonstrated this trait again and again, over decades. The US wants Russia to be the bad guy so they can probably justify nuking Russia or something, but Putin is not that person.