History of Tethyr

For the past 1500 years, Tethyr has had a single, strong royal family ruling with absolute power. When a king died or became incapacitated, his oldest son took the throne.  As the family trees of those close to power became more intertwined and complicated, there were the inevitable wars of succession and bickering over which second cousin was the "true" heir to the throne.  Civil wars were brief, however, and once the fighting was over the system returned to normal (until the next major dispute in a few hundred years or so).
The established re-occuring cycle was broken 10 years ago.  The current ruling family had been in power for over 350 years, so long that they had dropped their own family name centuries ago (no one even remembers it now) and simply called themselves Tethyr.  King Alemander IV was comfortably ruling from Castle Tethyr, and the country seemed happy enough, but there was a broad current of dissatisfaction among the people of Tethyr.  Non-humans were forbidden by law to own land, and since most rights and privileges accorded citizens were based on land ownership, they became second-class citizens as well.  Things were especially bad for elves, who were driven deep into the Forest of Tethir by royal armies.  Alemander IV took land away from rightful owners and gave it to nobles who promised larger contributions to the royal treasury.  These social and economic inequities, coupled with several harsh winters and bad harvests in a row, made the time ripe for a change.
It takes more than just a couple of lousy winters to depose a king however, it takes treachery as well. In the case of the fall of House Tethyr it took an ambitious general and an impatient royal heir. Prince Alemander grew tired of waiting for the robust Alemander IV to make room for him, so he struck a deal with General Nashram Sharboneth, commander of the king's largest army.  While Sharboneth marched his army toward Tethyr, bringing along a sizable group of angry peasants recruited with the promise of land reform, the would-be Alemander V downplayed alarming reports from the king's spies and advisors, silencing the most persistent permanently through murder or exile. By the time Sharboneth's army arrived and laid seige to Castle Tethyr, it was too late for loyalists to help.
As Sharboneth launched a direct assault on the castle (using the expendable peasants as shock troops), a handful of elite soldiers let in a secret entrance by the prince would eliminate key guards and open the gates.  At the same time, the prince (one of the few people allowed to see the king directly) would murder his father.  A fire set by the elite troops would destroy evidence of treachery; the general and the prince would emerge from the conflagration and announce a new, joint government.
The plan was executed perfectly, but only up to a point.  Sharboneth double-crossed the prince; his men were much too efficient in setting the castle ablaze, and Prince Alemander (along with most of his fellow conspirators) died horribly in the fire.  At about the same time, a spy planted on the general's inner staff by the equally duplicitous Alemander murdered the general and dissolved his body with a powerful acid before anyone could come to his aid.
To make matters worse, everyone had underestimated the resentment the people felt for the royal family.  Once Castle Tethyr began to fall, there was no holding back the mob.  In one night, the proudest, strongest castle in all the country was reduced to a smoking ruin.  Everything of value - fine tapestries, plates and silverware, furniture, jewelry, weapons, clothes, armor, paintings, statues, etc.- was either stolen, burned, or just ripped apart and stomped into the dust.
As news of the fall of the royal family spread, so did the chaos.  In what is now known as the "Ten Black Days of Eleint," anyone known (or even suspected) of blood connection to the royal family was put to the sword.  This led to some darkly humorous moments, as social climbers who had bragged just a week before of being a sixth cousin twice removed of a royal aunt tried in vain to convince an angry mob that they were "only kidding."
The nobles who were the biggest supporters of the royal family also came under attack, and some baronial keeps fell.  Local leaders who had adequately distanced themselves from the Tethyr family, or were popular enough (or feared/strong enough), survived.  These surviving nobles became the initial players in the fight to decide the fate of Tethyr.
One thing was certain; any leader or type of government that too closely resembled rule under the Tethyrs would not be accepted.  "Royalist" became a dirty word in Tethyr society.  The power struggle continues to this day, and there is no sign of it ending anytime soon.