Thread is gone. Free from this ancient scourge, the people of Pern prosper beyond all historical precedents. With AIVAS’ wise guidance, technology advances in leaps and bounds, with ancient techniques that had been lost to time coming once again to the fore. In a flurry of activity, many new Crafts were established. Among the many rediscoveries is the field of genetic manipulation, which is applied with enthusiasm to dragons, whers and flits. As a result of this, new ranks unlike any others begin to hatch and low-rank females began to clutch, but still dragon numbers dwindle in the absence of Thread.
Where there is plenty, there is greed. Holders and Crafters begin to squabble over who should get the largest share of the goods, and the riders can’t help but get involved. But these are not the worst disagreements. The Iron Guard resent the continued existence of dragons, and the meddling of their riders in the affairs of others. They see dragons as parasites; hungry mouths who serve only to give their riders a superiority complex. In secret, they design a weapon with which they plan to eradicate dragons once and for all.
The Iron Guard strike. Their weapon is no blade nor missile, but a poisonous gas that acts on the minds of dragons. The gas drives the dragons mad, making them forget the link to their rider and causing them to do all they could to flee human habitation. They instead begin to live in the wild, aggregating into organised groups called Aeries. The few riders who happened to escape the attack flee to the remote, formerly abandoned Barrier Weyr, employing a great many wher handlers to guard them.
Far from the unity of the times of Thread, Pern’s sapient creatures are split into diverse factions. The human Holds and Halls remain more or less intact, but the Iron Guard lives on, and the Resistance have their own secretive goals. Aeries of feral dragons dot the wildnerness, each with their own policies towards humans. Some are willing to trade, some kill on sight. Prides of wild whers have grown bolder in the confusion, leaving their old jungle refuges to claim plane and mountain. An uneasy peace has settled, but any sudden move could tip the balance towards all-out war.