More than 50 years ago
Thay, the empire nation across the Rudric, was a swelling empire. It was ruled by its cruel, conquering emperor, Tynathis. No one knew what he actually looked like, as no one had seen him after he took office. It is whispered by conspirators that he was murdered on his coronation night, and that his council just took over the job of continuous conquering.
While a cruel rule, it was effective, and Thayan merchants were very rich. They transported goods all over the world and could often even buy out local companies. Thayans either lived in luxury (if they were commanders, or profiteers/nobles/merchants), or rags (if they were soldiers, laborers, or anything else).
50 years ago
In their ever continuous search for superior military, the Thayan Empire began experimenting with dangerous arts. A form of manipulation now forbidden by the Paragons, they contacted another planar world. This contact warped their priests in terrible ways, and should have been a hint. But, because of their blind greed only saw a super weapon waiting to be exploited; they continued to force more and more to the terrible art. One day, they made a break through, literally.
They managed to break through the barriers of the two worlds. This day is referred to as the Black Day. Instantly, otherworldly creatures called Horrors (present on the Material Plane), and Etherbeasts (present only on the Earthreal Plane), poured through the gap, and in minutes had destroyed much of the Thayan Capitol. A black cloud exploded over the city, and to the present, it has not seen a minute of sunlight since. No person who remembers the name of that city will ever speak it, nor even write it. Even saying the name of the tragic place can bring to you evil spirits, not full ‘Beasts, but malignant beings none-the-less.
At first it appeared that the evil was content to sit at the capitol, and let the rest of the world be. It was realized later that the ‘Beasts and Horrors had simply been sleeping off the giant meal they had just taken. Too soon again they were on the move and the evil spread and devoured the entire continent of Thay in a matter of months. In that last time though, Thay reveled its other secret project: the Warforged. Made of metal and wood, the Warforged were infused with the highest magics and were, in many senses, alive. They were built to be soldiers, and they did their job beautifully; for a while at least. No army could have stopped the hordes of evil however, and when the last of Thay fell, the Warforged were released. Because they had no souls, and a terribly strange astral presence, the Etherbeasts left them alone. So even today, there are many ‘Forged wandering around, looking for a purpose in life.
The Thayan empire is no more. Instead, it is loose rabble of arguing and warring mini-countries that still somehow manages to get their noses everywhere and cause trouble. As the saying goes: “I may hate elves, and you may hate me, but everyone agrees: we all hate Thays!” It is whispered however, that the only thing preventing the resurrection of the empire is the rise of a competent and scheming warlord. The land is slowly healing itself, but is still scarred by ugly gashes of where civilization was once present and is now nothing more than a ripped out scab. The rest of the nation is a shattered power vacuum of warring city states and roaming bandits.