Internment Camp 371 was a Dominion prison facility located on an asteroid orbiting a gas giant planet, in operation in the 2370s. Originally built as an ultritium mine, the camp held many survivors of the Battle of the Omarion Nebula following the destruction of the Romulan/Cardassian fleet, including Enabran Tain. In the camp Jem'Hadar weapons were always set on maximum, which would vaporize prisoners for the smallest infractions.
Tain used the old life support system built into his barracks to create a subspace transmitter. The transmitter was used to send a message to Elim Garak. When Garak was captured attempting to track down the signal in 2373, he and Worf were sent to the camp, where they discovered Julian Bashir and Martok had also been imprisoned there, following their capture and replacement by Changeling infiltrators. Tain died at the camp shortly after, and Garak was able to change Tain's modifications to allow the group to contact their runabout left in orbit, and escape. (DS9: "By Inferno's Light", "In Purgatory's Shadow")
Several months later, General Martok noted that his time in Internment Camp 371 had "dulled" his reflexes. Worf himself told Benjamin Sisko of his experience of tova'dok with Martok in the camp. (DS9: "Soldiers of the Empire")
In a Section 31 holodeck program, Luther Sloan questioned the ease with which Bashir and the group had escaped Internment Camp 371. In the program, Internment Camp 371 was supposedly where Bashir became a Dominion sleeper agent after being brainwashed by Weyoun. Sloan suggested Bashir had been allowed to escape to gather information the Dominion would later collect. (DS9: "Inquisition")