Brohd Zellor as a Material World

BROHD ZELLOR AS A PART OF THE MATERIAL PLANE
How and why was Brohd Zellor created?
Brohd Zellor came to be just like the other realms and planets on the material plane. It winked into existence with a kind of instant and super-brief explosion of blue-white life. Wink, and there is was. The Idea of the Dwarves came from a group of gods looking for adventure, and looking for something mountainous. This group of deities made their plan and got together their blueprints, upon which the ethos of the Dwarves would be created. Other deities, even from other pantheons, added their ideas.
Liv, the goddess of creation, put it all together and began the process of making it happen. It took a million years of work, but she did it. Before them the gods had their archetypal Dwarven land, and they sent avatars to live there, and they watched their creation grow and evolve. They devised a way for the Dwarven people to populate other lands throughout the material cosmos, via a system of spirit and reincarnation. They watched over the People, and the People gave them thanks and worship (for the most part). Thus the Dwarves came to be, and thus they spread.
Brohd Zellor is a sub-continent on the world Summer's Tale, but it's actually another world unto itself in the material plane. It is an enormous planet, coming close to the size of the Sun in our Real Life solar system. A Sun-sized planet (covered entirely with Dwarf-lands, as in IDEA ONE below).
Much of the Brohd-Zellor world resembles some kind of Safe Haven plane.
The Deities who reside on Brohd Zellor are indestructible at their core. The material representations are only partially “them,” living as avatars of a kind. Their true divine spirits--their ultimate selves--dwell in more abstract planes of existence. They appear here as avatars so they can participate in Dwarven Life, which they were meant to do, so they say.

BROHD ZELLOR AS A MATERIAL PLANE
Brohd Zellor exists as a sub-continent on Summer's Tale. Its magic and status as the Vivid Land of the Dwarves does not change, but everything that happens there is connected geographically to the places around it.
It is still the archetypal Dwarven realm, and still all but isolated from the rest of the world. It still contains the three Mountains, but these mountainsoperate as portals to Divine Dwarven lands (Dwarven Afterlife and the Three Mountains ) … Places where Dwarven spirits go after death. Brohd Zellor is still a place for Dwarven spirits to wander between lives, and to consider what might come next. A portal of some kind is often still the best way to reach Brohd Zellor, as the Brohdzl Mountains are perilous, especially in the winter. Trekking there over the Brohdzel Range is treacherous to say the least.  Sailing on a sturdy ship can get you to the stony beaches of Twin Valley or the southwestern shores.
Many of the denizens of Brohd Zellor, in this scenario, do not even know a world exists outside the Vivid Land. They are isolated by mountains on all sides and have never needed to go elsewhere.
The Kiddzai are still a threat in this scenario, but their scope is smaller here. They so far seek to destroy only one small area of the world. Also, if/when they finish with Brohd Zellor, they may be a danger to other lawful parts of Little Dream.

IDEAS ONE and TWO BOTH (material and mythic)

Even Dwarven enemies are given to populate Brohd Zellor, for they are actually essential to the archetypal life of Dwarves. Troll, giants, orcs, dragons, and some ogres, volcano fiends / demons, dragonborn--all of these creatures make Dwarves what they are, and their role as such is very important. They lurk in the caves and walk the mountains and hills, and hold hordes of treasure, in a way that is even more perfectly archetypal than the situation (for example) in the Gimli Mountains.
It exists as a kind of archetypal Dwarven realm. Brohd Zellor is hyper-Dwarven, more Dwarven than Dwarven, vivid like a Dwarven epic story around a hearth-fire.
Brohd Zellor is for the dead, certainly, but just as importantly it is the land of the Dwarven deities who reside there, overseeing not just the reincarnation process but indeed all the processes of Dwarven life and its devotion to them. For as long as Dwarves have walked the material plane, or likely even longer, the Deities have had their divine dwellings in Brohd Zellor, keeping up the process of Dwarven life and civilization.
Each deity has their own realm in the Plane, be it small or million-miles large, over which they have rulership and influence and jurisdiction. These realms, or sub-realms, or often sprinkled amongst each other on the landscape. The different realms each have their own flavor, depending on the deity overseeing its Being.
At current time, there are indeed many sub-races of Dwarves that live materially in the Vivid Kingdom. These groups made it to the plane due to divine magical efforts on the part of their priest or priests. These magic-users were able to open up portals to the vivid land, and groups of dwarven people have passed through, to live out their lives in the new/old environment.
Brohd Zellor is perhaps not “safe,” but it is a place of great adventure and vivid experience, Dwarf-style.