The Dark Market was a major trade hub located on the fringes of the Delta Quadrant in the 23rd century. It was a colony located in a dense asteroid field, where it was embedded in the largest asteroid. Here it drew various merchants, smugglers and traffickers from across the Quadrant where they engaged in various stages of commerce and black market deals.
In the 2262 of an alternate reality, Eurydice was coerced into working for the Dark Market Syndicate when they took her daughter. She found the Federation starship, USS Enterprise, adrift and moving at sub-light speed. She then spoke with its captain, James T. Kirk via hologram, offering to tow them to a place where they could get dilithium. She then had her ship, the Spectral, tow the Enterprise to the Dark Market.
Eurydice then beamed Capt. Kirk over to the Spectral and then spoke to him about her reasons for helping him and his crew. After docking, Eurydice then took Capt. Kirk and his landing party to meet with a dilithium merchant, Grunthum. After making the deal, Eurydice then took them to meet the Syndicate, to get their blessing. However, Eurydice betrayed them in order to clear her debts with the Syndicate. Despite them giving her daughter back, Eurydice felt guilty for what she did to Kirk and his crew and helped them escape. (TOS - Eurydice comics: "Part 1", "Part 2", "Part 3")
The trading world is ruled collectively by the Dark Market Syndicate. All transactions made in their market needs to be approved and blessed by them. However the Syndicate dictates business on its own terms and usually in a cut-throat manner. Its only priority is to exploit any transaction and any new asset that appears in its territory. Short-term economic gain, such as slavery seems to be more accepting than long-term peaceful trade-relations.