History and politics
It was not known if the Yridians had a central government. The Yridians encountered by the Federation appeared to be loosely aligned and concerned with their own interests, often serving as hired agents for other races and operating as groups or individuals. They were often unwilling to reveal information they collect without payment. Despite their reputation, the Yridians were often seen on space stations and planets within Federation space. However, the shady dealings of some Yridians earned them arrest warrants issued by governments such as the Klingon Empire and their trading goods were often confiscated.

At some point before the 2360s, the Federation believed that the Yridian race went extinct. This disappearance was so total that it even convinced the Borg, who designate the Yridians as Species 6291, that the species was no longer in existence. However, Rudolph Ransom, a Starfleet exobiologist, discovered that there were some still alive and carried out First Contact. This act directly lead to his promotion to the rank of captain.

After this point Yridians were encountered throughout Federation space. A group of Yridians learned of the research of Dr. Richard Galen sometime prior to 2369. The Cardassian Gul Ocett purchased the information they had obtained, and the Yridians later attacked Galen's shuttle to steal further data. Their ship was destroyed by the USS Enterprise-D before it could return to the Cardassians with its findings.

A group of Yridians bought magnesite ore, stolen from a Pakled mining colony in the Kalla system, from the Duras sisters in 2370.

The Yridians were known to be targets of Maquis raids in late 2370 as Starfleet put together a Yridian convoy as lure for a Maquis attack. The convoy of six ships left Deep Space 9 for the Demilitarized Zone, destined for Cardassian space, carrying a supply of isomiotic hyposprays, plasma flares and quarantine pods.

Culture
A Yridian called Paltriss created several rings, later known as the Rings of Paltriss. They became extremely valuable and, as such, were removed from the Yridian homeworld over time. In 2370, Quark came into possession of forty-two of them.

The Yridians exported several beverages to the Federation, Klingons, and Ferengi, including Yridian tea, Yridian ale, and Yridian brandy.

The Yridian yak was also well known.

Technology
The Yridians operated their own design of starship, used as both a destroyer and as a freighter. Others were known to operate small warp-capable shuttles.