Previously called by its original creators "Terok Nor," this old Cardassian mining station orbiting the planet of Bajor was built in 2351 and abandoned 18 years later as the Cardassian occupation of Bajor came to a close and the Cardassian retreated from the system.
Soon after, at the request of the Bajoran provisional government, Starfleet assumed command of Deep Space Nine and gave it a Starfleet designation.
When the Bajoran wormhole was discovered nearby, linking the Bajoran system to the Gamma Quadrant, what had once been a backwater station became a bustling hub of commercial, scientific, and strategic significance, reflecting Bajor's new-found independence and strength within the Alpha Quadrant.
In 2372, the station upgraded its weapons and put them to use during an incursion with the Klingons, following the Klingons' removal from the Federation-Klingon alliance. The upgrade included several new phaser and photon torpedo banks.
From 2373 to 2374, the station was briefly overrun by a Dominion occupation force, which featured Cardassian troops.