The Barzans were an intelligent humanoid species native to the planet Barzan II. In appearance they had light-copper to tan skin, with some facial ridges and a hairline set far back from the forehead. When leaving their homeworld, they had to wear a breathing device that provided them with the gases found in the toxic atmosphere of Barzan II.
The Barzans were a resource-poor species, dependent on others for generations. They were technologically only moderately advanced, and they did not have manned space travel.
In 2366, a wormhole was discovered near their planet. The Barzans sent an automated space probe to collect data on the other end. They determined it was in the Gamma Quadrant, which was quite exciting since it meant they had a natural resource that other civilizations would invest in. It was hoped that the Barzan wormhole would open a new era in prosperity. This hope was a major factor in the Barzans' decision to sell rights to the wormhole to the highest bidder. Unfortunately, the wormhole turned out to be the "proverbial lemon". (TNG: "The Price")