I guess almost nothing was written about that time period. We’re talking about, what, one sentence or two?
What we know is that there was a conflict.
For all we know, there could’ve been Trolls fighting each other, Trolls on the Night Elves’ side, etc.
We already have them, they’re on the Alliance. We call them Night Elves now.
I feel like folks asking for more trolls or elves to be included into the game should watch this:
Just because there’s Forest Trolls, Dark Trolls, Forum Trolls, Troll-Trolls, Normal Trolls, and Abnormal Trolls as loosely mentioned tribes doesn’t mean each one needs to be a must to be implemented. If you are gonna suggest a race, at least be creative with it. When a Kitchen sink Elf is more creative than your idea … that’s a real problem.
Zul’jin was not a dark troll.
Blizzard should think outside of the box and call them Evening Trolls and they wear dresses all the time.
I was thinking about this the other day. They shouldn’t be in War Within, they should be in Midnight.
Think of it, Midnight is suposed to be a coming together of all the Elvin tribes. What if at the very end of WW leading us into Midnight we discover a lost tribe of Dark Trolls that were the pregenerators of the Night Elves and are stuck half way along the change into Elves. So they aren’t quite Trolls and not quite Elves yet either.
You could say that their underground home became too crowded millenia ago and some left to explore and they settled the shores of the Well of Eternity. But they still intermingled with their parent tribe underground. And when the underground tribe started to notice the change happening to both the Well tribe and themselves, they shut off all contact with the outside world, stuck somewhere between Troll and Elf.
They even have the perfect spot for their re-emergence. The empty part of the map behind Strathholm that borders on the Ghostlands.
No but it is funny blood elves don’t fall far from the tree. 
People seem to think all dark trolls evolved into Nelves and thats why we don’t have them. Wrong there were dark trolls in WC3 and there is a dark troll NPC in the game. One single NPC. Some evolved into Nelves and some stayed trolls because they didn’t get as much arcane exposure. But I like the idea of a race that is halfway between troll and elf. That would be very cool.
Also Nelves didn’t wipe out Shadowtooth clan, the most recently spotted Dark Trolls. That was the Twilights Hammer.
There is a female dark troll named Ik’nal in Dazar’alor in one of the little enclaves on the west side of the middle level. She’s very sad and says she is the last of them and a kind of exhibit.
I’m pretty sure she only says she is the last of her clan, the Shadowtooth, not of all Dark Trolls.