The Corellian Exclusion Zone was a zone in the space surrounding Corellia during the Second Galactic Civil War in 40 ABY. As the blockade of Tralus failed, this new one only enraged the inhabitants of the Corellian system and encouraged more systems to join the Confederation.
During the Blockade of Corellia, however, the Galactic Alliance military forces were keeping their heavy presence noticed by denying any ship to leave or travel to the planet which thus became totally isolated.
This was mainly for keeping food and material away from the orbital factories, forcing the Corellian government to surrender. The blockade also affected the shipyards of the Corellian Engineering Corporation very badly, which could get disastrous effects on Corellia.
Only ships of the Galactic Alliance military, or civil ships with special codes, could travel through the exclusion zone without taking the risk of being shot down.