So I’m going to talk about some Forgotten Realms lore. Specifically I’m going to talk about how elves are total dicks. Like most fantasy worlds riffing on Tolkien, Faerun used to be ruled by elves back in the era before humans were a big deal. Before that, though, was the era when dragons and giants battled one another for control of the world. How did we get from one to the other? How did elves take over from a world ruled by dragons? Numerical superiority? Aid from friendly metallic dragons? Alliance with the giants?
Unfortunately, the answer is dickishness.
The elves got together and cast a spell spanning the breadth of Faerun called the Dracorage Mythal, which causes dragons and draconic creatures to become more and more agitated around a certain time of century, ultimately completely losing control and descending into a bestial rage. During this time, they’re much less cunning and easier to hunt, and also prone to slaughtering their own neighbors, allies, and servants. This does not exclusively affect the evil chromatic dragons. Metallic dragons, quite a few of whom are quite kind and helpful to the humanoid races of the world, are affected just as much.
The elves had access to the kind of powerful magic needed to do this, so they apparently had a pretty solid academic tradition of some kind despite draconic rule. It’s not like they all got together and decided that a reign by disaffected tyrants suppressing the growth of civilization had to come to an end, no matter the cost, because the dragons were evidently leaving them alone to do their thing. It’s not like they couldn’t have excluded good dragons from the effects either, because the Silverymoon Mythal does exactly that. It’s a permanent, area-spanning spell (this is what a mythal is) that prevents chromatic dragons and only chromatic dragons from entering the city of Silverymoon. Elves could’ve targeted evil dragons exclusively, but apparently deposing tyrants wasn’t their goal. They just decided to destroy draconic civilization, good and evil alike, so they could take over.
Elven civilization lasted for fifteen thousand years, during which almost no events are recorded at all except the founding of various kingdoms. I do want to point out, however, that humans have been around since before the elves were, from the age before dragons and giants at the very dawning of Faerun’s history. Despite this, in the waning years of the elven empires, humans were still barbarian tribes. It’s been thousands of years of elven rule of the continent. There’s a couple of possible reasons for this, but none of them are pleasant. Maybe elves are actively hunting down humans who start to build up a settled civilization, or maybe they’re so xenophobic that they kill every human who enters their woods, thus preventing humans from having any awareness of elven civilization, which would stop them from imitating and kickstarting themselves into their own civilization. Whatever the elves did to keep human neighbors from emerging from the stone age over the course of several thousand years, it can’t have been very friendly.
Plus, there was the time when the elves got together to try and create a pure elven utopia and accidentally ripped the continent in half instead. I won’t get into the War of Three Leaves here, since that was mostly the fault of the dark elf kingdom of Ilythiir, and the dark elves are generally agreed to be dicks even by other elves. To give a very brief overview: Dark elves secretly interefere in union between multiple small elven kingdoms of mostly wood elves which causes them to descend into war.
The age of elves ended with as much dickishness as it began. The old elven empires came to an end due to the Crown Wars, a period of war between elven empires that lasted for three thousand years. Even in elf years, that is four centuries, many times the length of the Punic Wars or the Hundred Years War. The Crown Wars are politically complicated and involve a bunch of elven empires with elfy names that are hard to distinguish from one another (Ilythiir up there is a good example), so I’m going to simplify a little bit. The maps at this link may help you follow along (I have classified both green elves and moon elves as “wood elves” for simplicity, and have called sun elves “high elves” for compatibility with the 5e elf sub-races, because I don’t want to spend three paragraphs describing the minor differences between Forgotten Realms sub-races and regular sub-races).
A high elf kingdom thinks they have the right to vassalize a wood elf/dark elf kingdom due to an ancient marriage. The wood elf/dark elf kingdom disagrees, and negotiations for peaceful annexation fail. The high elf kingdom decides to go ahead and invade anyway. This is the casus belli for the Crown Wars: High elves decided they were entitled to wood/dark elf lands and invaded.
Now, the high elves are quite dependent on trade with those wood elf kingdoms the dark elves sabotaged back in the War of Three Leaves (which is five thousand years old, which is just shy of seven centuries in elf years, so about as relevant to the modern political situation as the Holy Roman Empire is to real world politics). The dark elf kingdom is too far away from the wood elf/dark elf kingdom being invaded to intervene directly, so instead they ask the wood elf kingdoms to stop supplying the high elves in their blatantly imperialist war of conquest against the dark elf kingdom’s little brother. The wood elf kingdoms aren’t just apathetic, they actively support the high elf invasion, despite the targeted kingdom being as much wood elf as dark elf. I mean, the wood elf kingdoms are actually a mix of green and moon elf kingdoms that I’ve combined together for clarity’s sake, whereas the targeted kingdom is a dark elf/green elf combo kingdom, so some (one) of the wood elf kingdoms actually have nothing but elfiness in common with the victim, but they’re still the victim. Regardless, the wood elves refuse to withdraw economic support from the invading high elves.
The dark elves launch a surprise attack on one of the wood elf kingdoms, the high elves’ biggest trade partners, and cut them off. Then they burn a second kingdom to the ground, and then light a third on fire with the help of some wood elf defectors. Now, the official histories paint these guys as traitors, but the limit of the dark elves’ crimes so far is 1) attacking without declaration of war and 2) using fire. The dark elves used fire to carpet bomb population centers, which honestly is pretty evil, but the “great betrayal” of the dark elves so far is that they used fire at all, because hippie elves care more about trees than civilian casualties. And let me be specific, when I say “wood elves” here I mean green elves specifically, so they are defecting from a high elf/wood elf alliance to a dark elf/wood elf alliance. That’s not much of a betrayal.
It’s not until the high elves finish conquering the wood elf/dark elf kingdom that the dark elf kingdom does anything actually evil in order to wrap up the wars they started in defense of a now defunct kingdom. They enslave monster races for use in the war, and also they make use of undead, which is always called evil but is usually no more evil than creating robot butlers depending on how well the writers of the edition have thought things through. The slavery thing is definitely not cricket, though. The dark elves cease their wars once their ally has fallen and they wrap up some loose ends, with two major kingdoms still standing between them and the high elves. I think this is important because while the dark elves could be painted as using their ally’s plight as an excuse to invade neighbors, they cease their expansion as soon as the validity of their casus belli has expired. They don’t continue their warpath to avenge their fallen brothers, they make peace.
At this point the high elf kingdom attacks a high elf/wood elf kingdom, one of the two that stands between them and the dark elf kingdom, for no reason. No casus belli is given in the history, not even some flimsy ancient marriage excuse, they just invade apropos of absolutely nothing. The dark elves don’t get involved, but it turns out they totally should’ve, because at the end of the war the high elves nuke the dark elf/wood elf kingdom. The one they already conquered in the last war. If you’ve ever seen the High Forest and the Great Moor right next to each other on a map of the Sword Coast? The High Forest was the sun elf kingdom, and the Great Moor was the dark elf/wood elf kingdom, and it was a forest until the high elves nuked it.
The dark elves are just a little bit put out by this turn of events, and both the dark elf and high elf kingdoms invade the final wood elf kingdom that stands between them. The wood elf kingdom withdraws from their eastern borders to let the two fight it out. This is when the wars get religious. The dark elves worship the spider goddess Lolth. They have always worshiped Lolth, even when she was a member of the elven pantheon in good standing. The falling out between elven chief god Corellon Lorethian and Lolth didn’t seem to provoke any particular enmity between their worshipers, but now it is for some reason a problem and the followers of Corellon get together and curse the dark elves, turning them black and forcing them underground (this obliviousness to racist narrative brought to you by the 1970s).
Then the high elf kingdom, who now basically rule the world, try to extinguish all the high mages and priests of Corellon Lorethian to stop themselves from ever being cursed the way the dark elves were. And now all of the sudden the elf kingdoms are uniting to stop this blatantly expansionist empire. That one remaining wood elf kingdom who withdrew from their eastern border during the war, a refugee kingdom of elves who fled the oppression of the high elves (that is not me editorializing, that is the stated reason in the lore for their flight from the empire), and a second high elf kingdom in the far north who’ve just sort of been sitting around watching the whole time all attack the first high elf kingdom. Although no formal alliance between these three kingdoms and the dark elves in the Underdark is ever made, the lore does state pretty unambiguously that dark elf raiding is the reason that the high elf kingdom was weak enough to fall to their remnant enemies in the first place. The end result is that nearly every elf kingdom has been destroyed and the age of elves is at an end.
And it is the high elves’ fault from front to back. They were the cause of every single war. To the extent that the dark elves turned evil (and while modern drow are clearly evil, the vagueness with which their atrocities are described makes me suspect that there may have been a wee bit of editorializing going on by the winners of the elf wars, who wanted to demonize both the fallen empires as having had it coming, rather than admitting that the church of Corellon Lorethian took the wrong side of the war), they turned evil as a result of the continuous war brought on by the high elves’ naked imperialism and blatant war crimes.
Now, high elves are far from the only dicks here. Even in the very best reading of events, the dark elves definitely engage in some war crimes of their own, and the magnitude of these war crimes is not lessened just because the high elves did worse. Likewise, the wood elves, who are quite consistently victimized by both sides, are still culpable for whatever led to the repression of human technology at the time (particularly since one of the wood elf kingdoms is the only one known to have had humans living within its claimed territories, the humans just lived outside of the woods where elves lived) and presumably had a role in the Dracorage Mythal, since that is attributed to elves in general. Faerun elves are all dicks.
And don’t get me started on Krynn elves. They don’t even pretend to be nice people.