The Parent Clans
Ages ago, before the Dwarvish clan known as Gemthain sailed for Adonthell, the three clans of Gemthain, Gildhammer, and Ringforge sought to make alliance. They did this by planning two generations of marriages. First, a son of Ringforge and a daughter of Gildhammer would marry one another. Their first son would marry the first daughter of a titled couple within clan Gemthain. The resultant three-way marriage of alliance was made several times in those two generations. A new clan, Uzdun'kal, or Gemcraft, was created with some of the wealth, skill, and status of the parent clans. The clan originated in Thukhuzdun'szhalrok (which means, Mountain Meadhalls), which were ruled by Zhet'kal (which is Gemthain) ere the greater part of the Gemthain clan went over the sea.
Uzdun'kal had some share in the gifts, crafts, wealth, and status of each of the parent clans, but the bonds between Uzdun'kal and Zhet'kal were particulary strong. For that reason, when Zhet'kal began to migrate south in search of other mountains to mine and new kinds of stones to work, Uzdun'kal followed. They traveled south along the spur of the mountains into the lands ruled by Elvish and Half-Elvish folk. Their paths lead them to the shores of a great sea, which they called Szhum'lhuzdu - the Sea in the Forest. They knew that to go west or east around it would lead them to the mountains eventually, but both paths seemed too long. Deciding thus, they built a settlement on the shores of the lake, cutting trees with permission of the Elves so that they could built boats to cross the water. They called their settlement Lhuzdu'rok, the Forest Hall, but they did not dwell there past need. Lhuzdu'rok is less than a memory now, save as a place where old tools are found in the earth.
Though they spent as little time as possible among the tall folk, they heard of a distant Isle which was large enough to have mountains. The leaders of Zhet'kal immediately became interested in the news of the mountainous island. Clan Zhet'kal already had a reputation for crossing water more willingly and in greater numbers than any other kindred among the Khuzdunat. They had crossed the Inner Sea, Szhum'szhalrok, which stood between the Meadhalls and the Mountain in the Sea. Indeed, though the Gemthains are skilled in many things, they were most revered, or the more ridiculed, for their mastery of lhuzdu, which the tall people call wood.
(A group from within clan Zhet'kal had crossed the straits to the Mountain in the Sea, west of the home ranges of the Khuzdunat. Then after, those Khuzdunat were called Khuzdunat'lhuzdu, the Woodcrafters. Members of Zhet'kal had moved freely between the home ranges and the Mountain in the Sea, and when Zhet'kal decided to move south to seek other mountains, those who wished to stay in the north declared themselves members of clan Khuzdunat'lhuzdu and remained with their near kin.)
The Journey South
When some among the remaining children of Zhet'kalek, the first Gemthain, heard the news of the Isle, they began to consider setting out to find it. Their plan grew in their own minds, and in the minds of their kin. So, when Zhet'kal and Uzdun'kal came to the southern mountains, Zhet'kal remained there only briefly, while they built their ships. They said that they would find Adonthell, though it was strangely and all too softly named, or dig their mines beneath the floor of the sea. Thus the only Dwarven city built above ground is called Uzthut'szhum - the Mine of the Sea.
So saying, they built their ships and set sail. Seldom did news of them come after they had sailed. In a long-passed age, they faded out of memory into legend. With them went the two diamonds which their father, Zhet'kalek, had crafted before the wives came forth. Like them, Uzthut'szhum is little more than memory now.
The clan of Uzdun'kal settled the southern mountains, though they were afterward joined by groups from other clans. Many are the mountains and the ranges of the south. Uzdun'kal and the clans which followed them spent many years exploring the skin of those mountains, and have not yet fully explored the roots. In time, each chain of peaks was named and claimed, but Uzdun'kal, who had come first and stayed longest, claimed the headwaters of the river running to the sea. Their halls they named for themselves. They meted out the underground rivers as one would mete out tools - wisely, but not unkindly. Thus, they are sometimes called the Riverthains, Zhet'szhom.
All news and trade in the south reaches Uzdun'kal eventually for among Dwarves, the Lord of Uzdun'kal is the first lord of the south. His trade is with Elves, Half-Elves, and Men. His wisdom is legendary, so we say that a wise person has the wisdom of Uzdun'kal.