Golden Hills

Golden Hills was a celestial plane in the World Tree cosmology model, and home to most of the gnome pantheon. During the Spellplague, it was set adrift in the Astral Sea and eventually merged with Arvandor. Before becoming its own plane, Golden Hills was a region in the Dothion half of Twin Paradises/Bytopia, according to the Great Wheel cosmology model.

Description
In the Great Wheel cosmology model, descriptions of the Golden Hills varied primarily in the size of the "hills". Some characterized them literally as a group of seven hills nestled in the center of Dothion, the "topmost" layer of the Twin Paradises. But it was also said that Baervan Wildwanderer's oak tree, Whisperleaf, grew on the side of mountain that was joined at the top to another mountain that rose from Shurrock, the other half of the Twin Paradises. Connections to this region were the same as for the Twin Paradises, but it was said that mine shafts in Flandal Steelskin's domain connected the Mithral Forge to digs on other planes, including Acheron, Baator, Concordant Opposition, the Elemental Plane of Earth, Pandemonium, the Quasi-Elemental Plane of Minerals, and Ysgard.

In the World Tree cosmology model, Golden Hills was a mildly good-aligned celestial plane connected to the trunk of the World Tree. Travel to and from other celestial planes could be accomplished via the World Tree as long as the Tree or its servants approved. The usual method of travel was journeying through the Astral plane, either spiritually by astral projection or physically by using plane shift or similar magics. There was a known portal to the realm of Gond the Wonderbringer in the House of Knowledge located somewhere on or under the hill belonging to Flandal Steelskin. Flandal's forges were heated by a portal to the Elemental Plane of Fire, but it is unknown whether this was a one-way or two-way portal.

Seven rolling hills rose from the vast plain, each hill belonging to one of the gnomish deities. Urdlen, the eighth member of the gnomish pantheon, made its lair in Hammergrim. All accounts agree that everything in the home of the Lords of the Golden Hills was suffused with a polished gold hue.

Inhabitants
The only native inhabitants of this plane were the devas, solars, planetars, and other angels that served the local gods. Gnome and svirfneblin petitioners made up the rest of the population.

Realms

 * Baervan Wildwanderer's realm was known as Whisperleaf. The name was taken from the huge oak tree atop the hill, from which Baervan cut his halfspear of the same name. It was said that the tree was actually a treant of the largest size and would attack anyone who approached it other than Baervan. A quaint and cozy cottage was near the tree, which, despite its small appearance, was large enough to hold all his petitioners.
 * Baravar Cloakshadow's realm was known as the Hidden Knoll. The Sly One set all manner of non-lethal traps, illusions, and misdirections at the entrance to his domain. It was said that anyone who got past them could have their pick of the treasures in his realm. It was also said that he changed the defenses constantly to embarrass the overconfident and ensure only the truly skilled would triumph. Petitioners lived in small thorps strewn about the hill and beneath the surface.
 * Callarduran Smoothhands' realm was known as the Deep or Deephome. This hill was the smallest of the seven, but the vast majority of this realm was underground. Svirfneblin petitioners had an affinity for this realm, even if they did not consider Callarduran to be their patron deity. It was said that despite the dense depths there were caverns of breathtaking beauty to be seen.
 * Flandal Steelskin's realm was known as the Mithral Forge. Almost entirely underground, a large petitioner's city sat atop a complex of mines, tunnels, and a forge heated by elemental fire. The hill reverberated with every blow of Flandal's hammer. It was rumored to contain a subterranean river of liquid mithral.
 * Gaerdal Ironhand's realm was known as Stronghaven. Heavily fortified, this hill contained a citadel that was the bulwark of defense for the rest of the plane. Gaerdal took security and protection very seriously and this realm was characterized by a utilitarian design and a distinct lack of the usual tricks, jokes, and shenanigans that were found in abundance on most of the other hills.
 * Garl Glittergold's realm was known as Glitterhome. The largest of the Golden Hills belonged to the patriarch of the pantheon, but he didn't spend much of his time in residence. He preferred to wander about the plane, often in disguise, playing practical jokes, encouraging unity and cooperation, and watching over his people.
 * Segojan Earthcaller's realm was known as the Gemstone Burrow. Another realm that was mostly subterranean, the Earthfriend filled his domain with burrowing animals, and together with his petitioners they riddled this hill with earthen tunnels of all sizes that joined pleasant lairs and comfortable homes.