Cardassian sector

From Memory Alpha, the free Star Trek reference.

The Cardassian sector was a sector of space located adjacent to Sector 21503, near the Federation-Cardassian border.

In 2367 the USS Enterprise-D was conducting a mapping survey of the sector. This sector was previously visited by Captain Picard while he was in command of the USS Stargazer. While there on the Stargazer he encountered some Cardassians and lowered his shields as a sign of good will, but the Cardassians took offense and attacked, taking out his weapons and damaging the impulse engines before he could retreat. (TNG: "The Wounded")