Wizards were once a great power in the pre-Sundering Sea of Stars, indeed the gods feared that it would be the wizards that made a play to displace the divine beings and so agents of the faiths were actively working to undermine the power bases of the great wizards and keep them divided. Unfortunately, the gods focus on the wizards caused them to almost entirely overlook the draconic conspiracy.
When the dragons attacked the gods, the wizards dithered, some arguing that the gods needed their help, others were happy to watch two rivals tear each other apart, most just waited and trying to figure out what was happening in the heavens. A handful of ambitious wizards in the immediate aftermath of the Sundering tried to caim their own independent states, the Empress offer them one chance to bend the knee to her, most did not and were destroyed in swift and decisive action. The other wizards either went into hiding or found draconic patrons, the choice was stark, avoid the eyes of the dragons or serve them. The wizards’ ruins were left behind by the Empress’ wrath, she forbid anyone from looting them, leaving them as a testimony to her power. Of course that has not stopped the greedy and the curious from exploring them, especially as Imperial oversight of the ruins fell away after centuries.
The wizards who found draconic patrons, most found them to be generous and willing to give them free reign as long as they produced the results there patron desired. Such pressure to succeed does sometime lead to the cutting of corners and taking of risks, such as hiring of venturers to acquire needed items or information.
Those who went into hiding pursued various tactics to vanish, some found patrons among the elves, dwarves or even the criminal underworld, others traveled to the wilds at the edge of the world where few went, other concealed their skill and power and posed as hedge wizards or scholars. Most managed to avoid detection by a few were swept up by Imperial forces or the Draconic houses to be pressed into service or executed. After a century, the wizards had either integrated into their new lives or died, but the power of these rogue wizards was vastly reduced and the Imperial project to find them was wound down.
Wizards and their machinations, abandoned towers and labratories, can serve as adventure locations and seeds. While not directly able to challenge the power of the dragons, the magic secrets of the wizards are a stepping stone toward equalizing the power imbalance between mortal and dragon.
Notes: Image of the Wizard Earl (Henry Percy, 9th Earl of Northumberland) by Nicholas Hilliard, held by the Rijksmuseum and is in the Pubic Domain.