The Snow Ghosts of the Alfar

Far in the northern end of the Scandes mountain range is a mythinc set of ruins built partially into the rock of the terrain. Partially covered by snow and rubble built up over the centuries, the ruins help show the length of time tyhe Alfar (Elves) have been active on Earth. This is one such sad tale that harkens back to the early years of their presence. Like so many of their early settlements, it hold the remains of a great people, and one forced into hardship & barely remembered, all despite the great riches that still lie within.
A great many centuries ago, a tribe of Svartalfar had came through from Svartalfheimr to the Underdark below the Scandes. Seeking to mine the riches, or at least act as middlemen for their distant kin, the Dwarves, they built up a series of defended settlements throughout the Underdark trading with the different Dwarven & Svartalfar buying & selling ores, gems, metal goods, mining gear, food, weapons & armour. Becoming quite successful they planned out a city. Knowing that there were other creatures above ground they could maybe trade with, they planned this city to be built at the northern end of the Scandes knowing that it could be easily defended from all but the most powerful of beings, they started work.
Taking roughly a century to build, they quickly & efficiently built it with the help of their trade partners, allowing them a stake in it's prosperity. They knew thay had to keep these same clans, tribes, and families happy & on-side they knew the help was necessary. Also, the added defence of the others would help protect their rear. For a good few centuries they prospered.
Then things started to change. Less groups showed interest and their own brought stories from deep below saying the tribes there were suffering the higher they came. Groups of white Kobolds were venturing down deeper from some unknown layer high in the Scandes. They attacked caravans, raided settlements & mines lifting food and precious metals & gems. They also seemed to be highly organised and they had no knowledge why.
Soon it became clear. A group of captured Kobolds mentioned a name, Birgin the Winter Storm.
By all accounts, Birgin had been biding his time, raiding settlements above ground in more central lowlying settlements for food & precious items. He was an ancient dragon periodically given to sleeping and didn't like the cramped warm Underdark, and when he first noticed the Kobolds who worshipped him, let them live & reproduce knowing he could use them later. When the numbers wher ehigh enough, he sent them out in to the Underdark to raid. Also, he had heard of the Svartalf city now, this one now dubbed Nysnoborg.
He was planning on isolating it and attacking it to get to their precious treasures.
Thinking they had time the inhabitants of Nysoborg thought they had time to prepare but were too late. Bubbling up from below came hundreds if not thousands of Kobolds, so many they and their allies (including a few tribes of Goliaths in the region) couldn't compete. In a single day, both sides were fighting openly in the streets, districtys constantly changing sides.
Evetually Birgin the Winter Storm flew in under the cover of a heavy winter snow storm. The firest the defenders knew was large blasts of freezing cold breath froze the defenders in place while the beating of Birgin's wings sent many blown out from their defended positions. Claws and a cave-sized maw tore into whole regiments of troops.
Whole-scale slaughter followed and a few hundred noncombatants escaped over the next day while their relatives & friends died letting them escape into hidden tunnels. Birgin got what he wanted taking a sizeable portion of Nysnoborg's wealth with him with the help of the Kobolds. Some of the latter stayed behind to garrison & populate the city in the process.
The remaining survivors clung to the edge of the city, and even by this stage, they were changed by the cold & icy conditions turning pale and wearing snow white clothing regularly. They survived around the mountainsides & in hidden lairs, while raiding their old city for other eresources secreted away near the edges. Sometimes they raid deep into Nysnoborg to reduce the Kobold numbers and a few forward bases have been set up in hidden parts of it. There they fight an ongoing war against the Kobolds attacking at the very centre of the city.
They know they will never have the same prosperity or numbers as they did, but there is always hope. When any are encountered most refer to them as Ghost Alfars, Snow Alfars or Pale Alfars. They are seen as now dying out with a low birth rate and the harshest conditions any Alfar has had to face yet.

"i've seen them, the Snow Ghosts or the Ghost Alfar, whatever they are called. Sad, pathetic, wretched is some ways to call them. A once great city of stone destroyed and all for the greed of a dragon. And a dragon that is as cold as his lair. They didn't deserve that. If I were alive at that time I'd have happily fought alongside them."
Floki Bigbeard, Dwarven berserker (now deceased).