King Midas
SOC-9
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As for the Sargasso, it seems to me that there is a "Calibration Point" somewhere in the earlier charts of the Spinward Marches that makes astrogation through that part of space a rather tricky affair.
There are two places like this.
The Lanth Horseshoe has rumors and some write ups of ships missing and weird happenings in J-Space. (See Challenge 44 & 46)
The Republic of Garoo has an unusually large, if not all that potent, navy because their system has a "misjump magnet" and they salvage anything that has shown up there since it was discovered. There are rumors that they are wreckers killing the crews that survive the misjump, or that they are just very bold pirates who use the whole "misjump magnet" story to cover their seizures.