A Comprehensive History:
Close to the end of the Fourth Pass, a strange dragon was hatched at Ista Weyr. The female looked like a Brown, and was roughly the same size, except for some strange minor physical details. Allowed to develop, the dragon showed mannerisms not common to dragons of the time, but was otherwise intelligent, competent, and sane. She was affectionately termed 'Desert', due to her fondness towards the sands of arid regions.
However, more surprises were in store; it was discovered this dragon was fertile. On her first clutch Hatching, two additional new colors emerged, each appearing to be odd gender-reversed variants of the usual colors, each with their own minor distinctions. As they grew it was shown they were not able to flame as effectively as the traditional colors, and as the Desert seemed hard-pressed to hatch ranking colors (Only one bronze came off the first clutch) while hatching two more of her kind, the Weyrleaders grew concerned. They felt the Weyrs were being threatened with an endemic of weakness, both practical and societal. Meanwhile, the riders Impressed to the new colors started to feel treated as outcasts as their number grew, and a rift opened between the colors old and new.
Instead of waiting for the issue to come to violence, both the original Desertrider and the senior Ista Weyrstaff came to discuss the problem civilly. It was eventually agreed the best solution would be to scout for a new location on the Southern continent, where the new colors can be tested without interference and leave amongst themselves. The Northern Weyrs and Holds agreed to send enough supplies and labor to construct a rather large Hold at the best place close to the scouted location, and a system was devised so the North could stay in contact despite the long distance involved; a special post would be held by a Dragonrider/Holder hybrid, and with a specific single mind to focus on the Weyrleaders of the north could communicate easily.
A location was scouted roughly antipodal to center of the civilized North, and Seposita Hold was erected against the delta of a large river present. The valley they discovered was vast, bordered on the east by a mountain range and to the west by massive cliffs, with a large savanna beyond before an arid desert region. In the eastern mountains a suitable Weyr location was sighted, and Liethleach Weyr was built inside.
During the Long Interval after that 4th Pass, the area prospered, and contact with the North grew more and more sparing as the area became self-sufficient and alive in its own right. Thread was forgotten as focus went to construction and territorial expansion, holds marched down the valley and spill to the cliffs above, Liath Hold provided resources from the bountiful forest at the southern fork of Seposita River, and a budding northern Tacaigh Hold refreshed and refueled eager holders looking to the savanna for excitement and open space.
Thread returned on the 5th pass 400 years later, initially taking the area by surprise, but Liethleach Weyr sprung into action and were able to prove themselves. Relaying this news to the North as was their obligation, they were met with indifference and a lack of interest; the North was busy with their own Thread and not concerned with them.
Feeling abandoned but buoyed by their success, Liethleach Weyr and Seposita Hold continued to flourish, unaware that the North was actually faring less well than they, and slowly the North's opinion turned against them. Why did they still have to watch these Southern upstarts and their weaker dragons? Soon, the Rider envoy's post was taken by a rider Impressed to a mutation color, and the North felt that traditional colors were in decline in the South and cut ties in disgust. They were rid of what they felt to be a sentient pestilence, the weakness was not present in their ranks and would never threaten them again, they need not bother.
Liethleach Weyr escaped the plague that struck the North during the Sixth Pass, having grown resistant to that Southern virus through generations of living there. A final two (ranking) colors of the gender-reversed variety emerged, that set of colors called the 'Terrains' variety, and two new colors emerged with an impressive three hides, a brown-sized male and blue-sized female that was capable of clutching.
During the 8th Interval, the second Long Interval encountered, the number of savanna holds doubled, and Tacaigh Hold was recognized as a regional power. Accompanying this outflux of available labor, Liethleach had grown to a very large size and required demanding tithes to support themselves, Seposita for the first time felt the sting of economic competition from Tacaigh and their own child-hold Liath. Seposita's population and that of their close-knit minor holds grew restless, dissent grew and Seposita's Guardsman corps increased greatly as paranoia and jealousy drove the people to fear attack from Holder or Rider. A large fort structure, Fort Sententia, was built around the estate and offices of the Envoy Rider, and as the selection process had provided both successful, and very loyal, riders to Seposita the position was chosen to lead the new Guard as Duke, the first major military power on Pern in a long time and as of the 8th Interval, only the second encountered. Seposita did not mirror their norther counterpart High Reaches in going on the conquest, but instead bid their time and ensured their city would be able to easily repel any invasion the paranoid citizens, and even more paranoid military leadership, feared.
Liethleach saw the changes around them, and also grew afraid, their backs to the range and boxed in by Seposita territory, they tried to alleviate the tensions. The Weyr started a plan to grow self-sufficient, buying large tracts of land and farming it themselves, enlisting the aid of several minor holds along the base of the mountains. But this denial of territory put Seposita in even more dire straits, and the purchase of land, though legal, was eventually seen as a gradual invasion without arms.
On top of this, a small but vocal faction within Seposita was growing; those who wished to reestablish contact with the North. They new it was the dragons Liethleach housed that caused the severance in communication, and believed that these dragons were in some way the cause of nearly all of their problems: they spread this information around, and it caught quickly with the paranoid public. They desired to do what they thought the North was too cowardly to undertake, and in doing so prove themselves to the Northern Holds. They wished to simply kill any of the non-traditional colors.
This group had over the Long Interval grown large and had members in several high positions within the Guard. They executed a coup outside the public eye and murdered the current Duke-rider, and agents within Seposita Hold spread even more dangerous propaganda about Dragons than they had been for the previous century. Liethleach, with its lands and several small Holds were viewed by the public- and once the Guard had been corrupted, by the authorities- as enemies. Minor skirmishes occurred around the minor holds near Liethleach as Northern Loyalists clashed with Weyr-Allied forces. The violence escalated, yet Dragon still refused to fight Man, the genetic programming long-bred strained but still intact.
As each group fought for their survival, Tacaigh Hold continued to grow until it really did rival Seposita for power. The Loyalists knew this, and feared being caught up on two fronts at once. They devised a plan to eliminate the Weyr in one quick move. Under the guise of peace talks, several high-ranking Sepositan officers entered Liethleach's Weyrbowl with an armed escort, unknown to the Weyr they were Seposita's finest archers, hand-picked for the task. When the leadership of the two sides met, these soldiers attacked, felling many Riders and with them, their dragons. Liethleach's leadership disintegrated in the opening volley, and they lost more than a quarter of the Weyr's dragon population before the first archer fell. Enraged, many Riders and Dragons dove straight for the group, sustaining even higher losses, but eventually eliminating the threat.
Less than a third of Liethleach Weyr survived, and these dragons scattered throughout the mountains, the forest holds of the ambivalent Liath, or to the savanna holds of Tacaigh and the desert beyond. The largest cohesive group left, the remains of Liethleach's Ace Wing, started gathering the dragons dispersed as best they could, and with Tacaigh Hold's help along with the smaller Corraigh and Gaineamh Holds, established a secret pact called the Friotaiocht, and the vast cave system beneath the savanna was given over to them and christened Athaithne Weyr nine years after Liethleach's destruction.
A year later Desert Isth had a clutch at the ruins of Athaithne, where a Sepositan plant managed to impress. She was Seposita's attempt to return to older tradition, and was met with suspicion and never really fit in. After the Weyrlings learned how to go between, the Sepositan and an Athaithne defector left for Seposita to resume command over the Guard. Now the race is on to see who can recruit the rogue Riders about the lands to their side.