Star Wars: Ashes of the Old Republic
When the rebel military command surrendered at the Battle of Sluis Van, the political leadership sued for peace. In exchange for cooperating with Darth Vader and turning over the few Jedi still known to be in the separatist systems, Emperor Palpatine allowed them to keep a small enclave of systems. Merchant interests kept democracy from taking hold in this new Corporate Sector, and the Corporate Sector Authority was created to maintain order.
Although they have some military forces, they pale in comparison to the Empire and are sufficient only to maintain control. They have no ability to project force outside the Sector, even if they wanted to.