The Dosi were a humanoid civilization native to the Gamma Quadrant, and allies of the Dominion. The Dosi placed great importance on business and were extremely aggressive negotiators, to the point that fatalities were not uncommon.
The Ferengi, represented by Quark and Pel, negotiated with the Dosi in 2370 to purchase 100,000 vats of tulaberry wine. When the Dosi were unable to fulfill the demand, they referred the Ferengi to the Karemma, an important commercial member of the Dominion. (DS9: "Rules of Acquisition")
Over the next two years, Quark would accrue a debt with the Dosi. In 2372, when Quark thought he was going to die, his debt to the Dosi was mentioned by Rom as among those he had to pay off. (DS9: "Body Parts")
Food and beverages
According to Michael Westmore, the make-up designer for the Dosi, their facial art designs are based on colorations found in tribes in Borneo and in the South Seas. (Michael Westmore's Aliens: Season Two, DS9 Season 2 DVD, Special Features)
According to the Star Trek: Star Charts, on pages 70 and 71, the Dosi were from the planet Dosi which was located in the Dosi system. The homeworld of the Dosi was a Class M world. The official name for their government was the Dosi Confederation which governed the planet from the capital city of Relxer-D. The dominant species on the planet was the humanoid Dosi. In 2378, there were an estimated 1.5 billion Dosi living on the planet. In the late 23rd century, the Dosi established trade relations with the Vorta. The planet Dosi was discovered as a result of the Gamma Quadrant Bio-Survey. Dosi system primary was a Class M star with a magnitude of +9.