La Ciudad de Carne
The Great Sea Of Sand
The history of the Bloodrend is attested to in archives across the Great Sea of Sand - ten generations ago (give or take some, as determining dates from that era is a difficult business), the Great Sea of Sand was facing worsening water insecurity. Mages developed a form of magic around dehydrating something in order to provide hydration to another. It stsrted with plants - but it didn't end there.
They were driven from the cities of the Great Sea of Sand by force when their crimes were discovered, and use of the magic on animals or sapients alive or dead was outlawed. Unfortunately, this magic allowed the cult to survive deep in the desert, away from the water sources guarded by other Dextroluma. Over time, their magic refined into a religion. Their towns and buildings are made from bones and skin - not that many visitors tend to live long enough to talk about it... The religion of the Bloodrend revolves around meat and blood, and is quite violent these days.
The Bloodrend are often seen as something of a myth these days. Even when Dextroluma say they've encountered another Dextroluma in the depths of the Great Sea, they usually describe being helped. Of course, the ones who weren't helped don't generally survive to talk about it - and the ones who do somehow escape are often afraid to do so...
Occasional Bloodrend do leave their home, but they are generally sworn or cursed to secrecy about their past. Not that many would want to risk speaking about it anyways - in the parts of the land that are fully ruled by the Queen, it would surely lead to imprisonment at the least.