Background on Kuldahar

Kuldahar never really existed.

Obviously true to those outside the D&D world, but also as far as official cannon, it was never touched upon by any author or agent of Wizards of the Coast until Black Isle Studio's game.  It only appears in the map that came with the game which was artistically stylized:

Forum user Ineth traced the various journeys of the adventures in the region using a map from Candlekeep to suggest some various possibilities of a village on the south side of a mountain with various access points to a green valley, volcanic fissure, warlord cemeteries, and unknown temple/monasteries.  This is the best approximation:

Following the success and fan enjoyment of the setting, there has been a gradual increase in the acceptance of Kuldahar as a place.  From this and referencing in-game lore, conversations, and later pdf's, a history of the place up to 1281 can be established.

Silvanus himself planted the acorn in the hills that later would become mountains.  He named the Great Oak "Kuldahar" and helped it to grow for 1000's of years until discovered by a Silvanite who turned the site into a shrine to the Oakfather around 1220 DR.  The shrine eventually also attracted travelers and merchants.  Later, the archdruid and the circle thought these to be travesty to the wild nature that they held dear and so expelled the people and set up thick natural barriers to prevent any new access.  In 1256 a new archdruid came to power and reversed these ways, seeing the warmth of the tree to be opening arms to shelter all.  He in turn was succeeded by Arundel, who is the last known archdruid of Khuldahar.

Outside of this tale, nothing else is known of Kuldahar and its fate.  The only conjecture is the the potential "Year of the Shattered Oak" 1313DR.  The roll of years do not necessarily match events in the world, but often they did.  Perhaps the shatter of the oak is reference to the the Tree Ghost Uthgardt tribe breaking from the Blue Bear tribe, but they have no specific reference to Oaks.  I think this allows for great story telling opportunities until something more official is passed down to us from Wizards of the Coast.  There at times feels no space left to be "unexplored" in this world, but the Spine of the World does offer that chance, and perhaps hidden valleys and villages found there could be just exactly what the Bard ordered.

My own personal idea of current (1490 DR) status is that the tree perhaps was indeed destroyed but there is a new one growing out of the old, and that Orrick the Grey is still there.  He is now the resident druid, combining his studies of protective magics and mythals with the sheltering power Silvanus gave to that place.  Perhaps in exchange for his service, Silvanus is granting him the gift of old age, thus allowing the story to, branch, across time.

Also important to note for the significance of the village is it was the traditional home of the Heartstone Gem, a powerful scrying artifact found in the roots of the tree (specifically the archdruid's home).  At one point a young druid out of jealousy or perhaps some other purpose fled with it, ending in the possession of a mystery temple.  This would then become a plot device for the original story as it was sought to aid in answering the fearful question of what was the source of the elusive and unknown evil that was encroaching on Kuldahar and all the North.