After double checking to see if I could find out the details of the conflict, I think I messed up.

So, the population was 25k, rather than 250k

Second, every single resident died, but it wasn't from the Orcs, instead being because a Dwarven high priest summoned Aurgloroasa, a shadow wyrm, in the middle of the city who proceeded to turn every dwarven resident into undead. It was then taken control of by 3000 human troops before it was captured by the orcs until the Dwarves recaptured it from them.

I know next to nothing about Forgotten Realms, but the events within evidently abide by D&D 5e lore if it's mentioned in official material, and the wiki for it had this to say on their relationship:

[quote]the entire (Dwarven) race had more or less declared war on goblins and orcs as a whole[/quote]
[quote]Given the racial enmity between dwarves and orcs and the importance dwarves placed on lineage, it was easy to understand their temptation to hold distrust and resent half-orcs. Half-orcs meanwhile thought dwarves would be funny if not so dangerous, for despite their capacity for drinking and raucousness they were serious, judgmental, task-oriented, and strict. However, half-orcs held respect for the strength and martial prowess, and further admired dwarven skill with stone and honesty while sharing an appreciation for simple pleasures. Dwarves were predisposed to letting those so inclined prove themselves, and the two could be surprisingly staunch companions, to the point that less traditional clans would adopt particularly worthy half-orcs, demonstrating the possibility for even the oldest grudges to be wiped clean.[/quote]
It's an optimistic spin on their relationship, though I'm not surprised it ends at the first sentence of this quote for the barmaid kicker IC.