The Gamma Quadrant is a designation for one quarter of the Milky Way Galaxy. The Federation defines its boundaries by the line that passes through the Sol system and the centre of the galaxy and a perpendicular line through the core. It borders the Alpha and Delta Quadrants.
The Gamma Quadrant was connected to a point in the Alpha Quadrant by the Bajoran wormhole. The two apatures of the wormhole, the Bajor system and near the Idran system, were around 70,000 light years apart.