Before Merakor's fall, only thri-keen and a few barbarian humans inhabited the isles. Even then, Krentismar wished for the Isles to be a Tehran sanctuary for the thri-keen. Any and all things born or arriving at the Isles must be bound to the Allegiance of Blood or are killed outright. In this way, Krentismar maintains the Isles as a sanctuary. It was never an issue until hundreds of thousands of refugees from Merakor needed to be saved from the drow.
At the end of the Kinslayer Wars, Alerius (a denizen of the Isles) convinced Krentismar that bringing the survivors to the Isles would be a good thing for the Isles. The nexal inversion caused by both Merakor's rise (towards Creation) and fall (to Chaos), made the entire universe of Tehra susceptible to whatever would happen next. Alerius speculated either Chaos or Warp would reign for millenia to come. Though it is not known how Alerius persuaded Krentismar to agree, what is known is that Krentismar contacted the archmagi protecting the refugees and offered them an much stronger Allegiance of Blood.
That is, each and every refugee had to take the Allegiance of Blood and bind their children for all generations to it. While people may continue to worship their own god, it moves their faithfulness through Krentismar's dominion first. This extra power is granted to what Krentismar names "Slayers." These are chosen exemplars from the races of the Isles whose sole purpose is to eradicate anyone compromising the location of the Isles. When the refugees arrived in what is now Taysor, the Allegiance of Blood also revealed traitors, spies, and creatures working for the drow in their midst. Demons, devils, slaads, dopplegangers, and other creatures became revealed and the thri-keen slaughtered them all. Alerius and the Court assisted. It is said that the beach sand was permanently stained red and when red tides wash ashore there, visitors report specters and hauntings as the slaughter is recreated.
The AOB has some interesting effects:
- Leaving the sanctified domain of the Isles, locations, names, and any landmarks that would enable even a mind-reader to see and know, is confused with other real places and people throughout Tehra
- Even under duress, torture, and magical interrogation by a god, the location of the Isles is not revealable
- Summoned creatures can come to the Isles just fine but the summoner cannot, for the life of them explain exactly where they are
- Recollections of maps change to the point that any attempt to draw or show an outsider where the Isles are results in total confusion
- Persistent attempts to reveal the Isles summons a Slayer who kills anyone involved in the attempt
- Attempts to take maps of the world or that would help determine the location of the isles, even a journal entry noting where certain stars are, make it so that the book, map, or whatever (tattoos even) cannot be taken off the isles. If tattoos, they have to be removed. Tania studied this with the minotaurs... affected people will become insane and self-mutilate themselves to hide such markings. If they are magically or physically prevented, a compulsion grows in the jailor to remove the markings. They'll late remember them as "offensive."
That isn't to say that extraplanar powers don't want to find the Isles or know where they are. It's like Atlantis in our world... the Hell Lords know, even Orcus knew, that somewhere was a place called the Isles. Orcus even visited the Isles many times and knew Bloodstone and Morbatten personally... but could not name them or find them again once he left... because Tehra is not these gods' throneplanes and they are not omnipotent in Tehra; Krentismar is. If you think about summoning or gating creatures through, rarely do you find the summoner going, "Here's my address. This is exactly where we are." When Orcus came through, it was because of Bomoki's Gate. Bomoki did not summon him to the Isles, but to Tehra. He just happened to come through on the Isles.
For any and all creatures, the experience is confusing but quickly fades or resolves itself to some other memory. "I couldn't have been in Atlantis. I must have been in this other place," they remember later. For residents of the Isles leaving, special arrangements must be made.
- The first Tauran world galleon to arrive in the Isles came near it by coincidence. The Court of Patriarchs helped them cross and then those Taurans had to abide by the AOB. As such, only a few of the Tauran fleet travel to Tania. They know that so and so captain and his crew go there, but they know - after much frustration to not even bring it up. When the ships leave, a cleric of Krentismar uses powerful quest magic to create programmed memories
- Directions to the Isles are locked in a chest and hidden. Once hidden, the captain cannot remember where or what they are
- When their mission conditions are satisfied, the captain remembers the box and its directions
- When they reach the directions, they remember to trigger certain magics
- Assuming they were not followed or being watched, the captain remembers the next thing and begins slowly taking the ship closer and closer, until they cross the threshold and remember everything
- If the captain dies, the First Officer inherits the captain's magic
- And so on
The Taurans tested this by torturing several of the first to death. Daryx also conducted similar experiments with extraplanar creatures, even following them back to their point of reformation. His studies confirmed that the AOB endures death. Remember, any god is omnipotent within its dominion and Tehra is Krentismar's, and the Isles are his sanctuary.