The Hall survived the Coming of the Dark at great cost in life but they were not routed as many others were. Great partsof the Hall were destroyed or haunted by the Dark but many sections remained untouched due to their highly defensible nature. The residents of the Hall kept controll of their main food sources and, as such, were able to hold out until the Dark disappeared.
Now, the Hall has rebuilt much of what was destroyed but they have yet to rebuild their population to it former level. Dwarven population growth is a slow process and the dwarves of Silver have accepted many non-dwarves into the Hall to help offset the population drop.