Baron Sengir created the barony when he was first stranded on the plane. The Baron found refuge from the elements in the swamps, dominated the local An-Zerrin peoples, and took over a nearly-completed Dwarven castle. After driving away the dwarves and consolidating his domains on the marsh, the Baron decided to populate his land. For years, Sengir set up his Dark Barony, using all the wit and guile of a demon. He ordered his subjects to kidnap people from Aysen. He also stole an entire vessel carrying thirty one families from Onella to Kerselin, forcing them to relocate to the deltas around Castle Sengir.
The immediate terrain around Castle Sengir consists of a variety of small villages built on barges or raised from the swamp on stilts. The mists cloud the sky, casting a perpetual night. The inhabitants live under Sengir influence and rule, making the best of their harsh living conditions. There are those in the villages who are the Sengir Autocrats, those chosen to transfer information and keep an eye on the villagers, but they have no real power in the Barony whatsoever. At the center of each of these towns lies a mucky graveyard. When any of the villagers dies, they are buried whole in the graveyard, and turned into undead for use in the Baron's castle.
In fact, though the humans who live in the squalid muck are important to Baron Sengir for the work they perform, for him their more valuable trait is that they all will die. Because mortals are constantly plotting the Baron's downfall, they are far more useful as undead servants in his castle, as unwavering warriors who guard Koskun Falls, or even, occasionally, as coat racks. Furthermore, the Baron enjoys the occasional flailing of a human for entertainment.
To keep the villagers from escaping, Sengir instigated firm rules: if one person tries to flee the Barony, the Baron would murder ten people in their place. However, since the only ways out of the Barony are through the Dead Zone, up through the windy road leading to Koskun Keep (guaranteed to be captured by his servants, as the path is barely wide enough for one person) or by sea (where his vampires watch the coast), few have ever made it, and the repercussions on their families and friends were terrible.
When Eron became lord of Koskun Keep, he and the Baron worked out a secret deal: Eron would ensure that the Sengirian Villagers were getting food and necessities that the growing population could not create themselves, and Baron Sengir would take no more hostile actions against the denizens of the Koskun Mountains.
- Matt Cavotta (February 15, 2006). "The Royal Bloodline (Emphasis on the blood)". magicthegathering.com. Wizards of the Coast.
- Doug Beyer (Wednesday, September 02, 2009). "The Planes of Planechase". magicthegathering.com. Wizards of the Coast.
- MagicTheGathering.com Staff (October 19, 2009). "From the Library of Leng: Baron Sengir". magicthegathering.com. Wizards of the Coast.
- D. G. Chichester (February, 1996) "Homelands
- Monty Ashley (August 10, 2010). "Welcome to the Barony". magicthegathering.com. Wizards of the Coast.