A Bajoran colony founded on the far side of the wormhole in 2370 and wiped out by the Jem'Hadar later that year as a warning from the Dominion.
New Bajor was the first Bajoran settlement in the Gamma Quadrant, established after the discovery of the wormhole. It is never seen. In Crossover, Bashir and Kira are returning from the opening of a hospital there when their runabout slips into the mirror universe.
In The Jem'Hadar, the Dominion soldier Talak'talan beams into Ops on Deep Space Nine and informs Kira that the colony has been destroyed. He remarks, with apparent respect, that its people fought well for a spiritual folk.
The massacre, together with the loss of the USS Odyssey in the same episode, marks the Dominion's declaration that traffic through the wormhole is an intrusion on its territory.