Halassur (spoilers)

Politics
The current Emperor of Halassur is named Tevqar and is in his twenties when the story begins.

There are other nations on the eastern continent that aren't part of the Halassurq Empire. Two of these, the Mahru and the Sindhul, sustain backchannel communications and a measure of trade between Halassur and the Hegemony even in time of war. A Sindhul is currently the senior trader/diplomat in the Merchant's Pale in Grand Shayard.

Society
Halassur prides itself on not being a slave empire like the Hegemony. "The Halassurq Empire did traditionally enslave captives in war – and still does, when it can get them. But three centuries of increasing military focus on a single front, where prisoners are scarce because of heavy reliance on Theurgy and Plektoi, have changed its society in lots of ways." (source)

Notably, "they harvest blood primarily from their firstborn children rather than from a slave caste." (source)

Halassur is a strongly gendered society with a pro-natalist policy in which women of childbearing age are expected to bear as many children as possible. This isn’t because most of the kids will be sacrificed–the firstborn usually suffices–but because the war consumes so many lives. The lack of Wards on the Halassur side mean that a lot more people die there than even in the horrible border areas of Erezza. (source)

Magic
The Halassurqs (like their cousins, the Brauracha and the Nyr) had an independent magic tradition back when no one had yet figured out how to use other people’s blood as fuel. The alchemical basis for aetherial blood was devised/discovered in Karagon and figured out a few decades afterward by Halassur–just in time to allow them to put up a decent defense against the Karagonds. (source)

Halassur uses Theurgy for agriculture to sustain its large population. But they overall need a significantly lower blood volume than the Hegemony, and would need markedly less if the war with the Thaumatarchy ended. Of course, one hope of many Halassurq generals (and perhaps of Emperor Tevqar) is that if they do finally defeat Karagon, they’ll learn the secrets of some of those distinctively Hegemonic Theurgic feats like ward-building and mountain-floating, and scale up their blood economy by mass-Harrowing the Karagonds, Erezziano, and anyone else who doesn’t fall in line. (source)

Theurgic education in Halassur has been very restricted -- until recently. (source)

Religion
The Halassurqs worship a pantheon of Mother Ummay, Consort Kormuz, and Evren the Firstborn. The MC will be able to choose to join this religion in later games.