"Clans", or sometimes "the old clans", refers to a number of nomadic tribes that roamed the verse during the early gray period of the Age of Darkness. It is important to distinguish "old" from "ancient" in this context, as "ancient" refers to anything pre-dating the Age of Darkness.
There may have been rivalries between some of the clans, but largely the names seem adopted to differentiate amongst themselves. The clans were nomadic for the early part of the age, but began to plant towns and cities towards the end. Only the Wolf and Lion clans are known to remain distinct entities through the Mage Wars, with the Wolf Clan disappearing around the end, and the Lion Clan becoming the nation of Bur'I.
These are the clans known to have existed:
The Wolf Clan
The Wolf Clan is the oldest and most distinct, with evidence of their existence dating back to the very begining of the Age of Darkness. Unlike the other clans who would later abandon nomadic life, the Wolf Clan continued thus throughout the Mage Wars.
Sometime near the end of the Second Chaotic Period the Wolf Clan was completely annihilated. Their numbers were believed to have dwindled to the hundreds by that time, and the survivors may have simply disbanded perhaps as late as B.G.A. 10+/-5. Ardrith, the last known member of the clan, married Kimi Bur'I, one of The Ten, and probably lived out his days in Arindell. They are never the less believed the ancestors of the Loup Garoux.
The Lion Clan
Strongly tied to the Wolf Clan, maybe even a direct offshoot. The Lion Clan inhabited one of the earliest known cities during the Age of Darkness, which they later abandoned. Perhaps the most distinct feature of the Lion Clan lay in their ability to adapt; being one part nomadic and one part sedentary, they would build cities and towns and abandon them as the need arose, at times relocating their entire civilization.
Though they stopped being the Lion Clan around the beginning of the Mage Wars, they continued as the nation of Bur'I.
The Goat People
Distinct in that the oral history remembers them as the "Goat People" and not the "Goat Clan", they were probably a more loosely-bound coalition than a clan. They were known to have been the first to domesticate livestock in the Age of Darkness. While most clans were still hunter-gatherer groups, the Goat People were breeding and raising animals for food, clothing, and transportation.
The Goat People would eventually settle with towns and cities established by other Clans, bringing their skill with livestock. Because of this, no modern culture can trace its roots to the Goat People.
The Bear Clan
Also known as the Drack, the Bear Clan settles primarily south of the Erum Range. At some point during the mage Wars, the Drack developed advanced sciences that led them to large-scale production of atomic weaponry. This would eventually cause an enormous backlash from the neighboring Marcon Alliance and pollute a large portion of the Greater Continent. The surviving Drack were forced to the Agras Plain.
The Deer Clan
Also known as the original settlers of Ebeta, making Ebetans most likely members of this clan.
The Moose Clan
The Snake Clan
The Rat Pack
Probably an inside joke and not an actual clan.
The Dragon Clan
According to oral tradition, the Dragon Clan were the fiercest of all, making frequent attempts to conquer other clans. They survived mostly by raiding neighboring clans, taking what they wished.
However, by the beging of the gray period of the Age of Darkness, the Dragon Clan seems to have been completely extinct. Since no modern cultures can trace their origins to this clan, it has been speculated that they did not exist at all.
The earliest verifiable accounts of the Dragon Clan date from the middle of the Dynastic Period of the Mage Wars, specifically originating from the Marcon Alliance. Based on this evidence, it has been proposed that the Dragon Clan was an invention of the Marcons, who created the myth of an old clan and claimed it as historical precedent to justify present injustices.
The Lamb Clan
One of the most common clans, the Lamb Clan had a great many branches. They were also able, in some fashion, to use the still functioning Roads, so that by the end of the Age of Darkness, their progeny had spread to many worlds.