I solemnly swear to obey, fight for, and maintain, the laws of the By-Laws of the Confederacy of Independent Systems.
—An oath of allegiance to the Confederacy of Independent Systems
The Confederacy of Independent Systems (also commonly known as the CIS, the Confederacy, the Separatist Alliance, or just the Separatists) was an interplanetary Confederation which was made up of tens of thousands of planets and systems, and also business conglomerates, which refused to abide with the corruption and obliviousness of the Galactic Republic any further, and followed disillusioned Count Dooku's fiery message of resistance to the hypocrisy of the Republic Senate.
Formed primarily of Outer Rim planets, and well some Mid Rim planets, the CIS was generally preferred by the largely anarchic Rim worlds, many of which didn't wish for the centralised Republic to absorb their worlds, many Outer Rim citizens viewed the CIS as a government in which they could have representation in a galactic government, yet not have that government interfere in their planetary affairs too much.
Eh, we don't need no damn corrupt "Republic" coming here and trying to tell us our business! Them Republic busybodies can stay on Coruscant! I'm a Separatist sympathiser, and damn proud of it! The Outer Rim as a whole should join the Separatists, at least the CIS is mostly made up of fellow Rim worlds who understand us, not some rich Core worlds who look down on us as primitives, whilst wishing to take what little wealth we have for themselves!
—Gavran Markin, leader of the Twin Suns Separatist Brotherhood, explaining his views on his disdain for the Republic and support for the Separatists, expressing the views of many Separatists
From 21 BBY with the Confederate-Earth Treaty of Alliance the Confederate States of Earth became a member of the Confederacy, the Confederate States of Earth loyally served the Separatist cause until the very end of the Clone Wars, successfully defeating two invasion attempts by the Galactic Republic, following the fall of the Confederacy and the end of the Clone Wars the Confederate States became a Separatist holdout before being defeated by the Galactic Empire in the Third Battle of Earth of 18 BBY. To be continued