From The Last Days of Summer, by Senior Scribe Leopoldo at the University at Lygia
Despite the best efforts of scholars throughout the known world, no written records of any kind have been unearthed dating earlier than the Cultural Revolution of 2300-2000 MBL [Moons Before Liberation], which understandably makes studying the rise and early culture of the Seelie Bureaucracy a somewhat difficult proposition. While extensive documentation exists of the Bureaucracy in its last incarnation, all information about its early days by necessity comes from the unreliable and somewhat biased memories of ancient gods…
[…]
The Bureaucracy first rose as part of the First Turning [of the Seasons from Winter to Summer] somewhere from 7000-6000 MBL…
Elvish culture, even the comparatively more sophisticated Seelie, bears little resemblance to our own, despite both races nominally belonging to the Summer house. Elves are universally sociopaths, unable to even consider courses of action that do not benefit them in some way. The only constraint on their actions is the oaths they have sworn, and the only difference between the "civilized" Seelie and the barbarous Unseelie is the greater ability of the former to subordinate short-term to long-term self-interest.
[…]
In 6000-5900 MBL, the invasion plan came fully into fruition. The Seelie forces marched on the men and the dwarves, slaughtering them wholesale and sacrificing much of the remainder to the Elf Gods, who used their newfound power to cull the rest of the Summer pantheon. For this reason, very little is known about early man or dwarf culture, or the non-Elf Summer pantheon...
The Seelie elves held on to complete power over Cael until the Cultural Revolution nearly 4000 moons later, but it is difficult to call what they did "ruling". They brutally exploited the servant races for labor and amusement while destroying any potentially threatening technology, but otherwise left them alone.
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The Cultural Revolution, when it came, came quietly and slowly, to the point where the Seelie did not even realize how much power they had lost until it was too late to reverse the trend. The gift of writing to humanity by the god Lucretius and runes to the dwarves by Hallr allowed complex social structures to blossom quickly over long distances, and new technologies to develop faster than the elves could stamp them out. The nascent societies formed during this period would later form the core of the modern political landscape.
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This third attempt at armed revolution against the Bureaucracy succeeded where the others failed for a number of reasons. First and foremost was the presence of significant internal strife over the Chancellorship among the Seelie themselves… Second was the invention of the steel-making process, allowing the equipment of rebel armies with superior weaponry to those carried by their oppressors… Third and possibly most importantly was presence of significant divine support for rebel operations. The Author and the Angelic Legion were utterly invaluable in dealing with the Elf Gods and providing magical support to the rebels' conventional forces…
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At nearly 900 MAL [Moons After Liberation], the present time at the moment of my writing, there are still pockets of elves living north of the Boundary River, but they are mostly Unseelie, few and far between. A remnant of Seelie power still exists in the South, but it remains too small to challenge the current powers of steel and magic.