The Inner Rim, originally known as the Rim, and also called the Inner Rim Planets, or the Inner Rim Territories, was a region of the galaxy between the Colonies and the Expansion Region.
During the Pre-Republic era, several worlds in the region including Denon and Manaan were ruled by the Rakatan Infinite Empire which contained various worlds across the Galaxy.
The Inner Rim was originally just called "the Rim" when discovered during the Expansionist Era of the Galactic Republic. It was first settled by the Republic in 20,100 BBY during the Great Manifest Period and was expected to be the farthest extent of the known Galaxy for centuries. However, the Expanded Rim (later renamed the Expansion Region) was opened within a hundred years of the Inner Rim. Due to their closer proximity to the hub of galactic civilization in the Core Worlds, the Inner Rim was later included in the Greater Core and Inner Rimmers gradually developed a condescending attitude towards those of the "outer galaxy", ironically known as the Rim like the Inner Rim itself in ancient times. Nevertheless, Inner Rimmers were looked down upon by the inhabitants of the Core and Colonies.
Between 5200 BBY to 4600 BBY, the jungle world of Onderon was settled by shipwrecked human colonists who established a civilization centered on the city of Iziz. In 4400 BBY, the planet was taken over by the Dark Jedi Freedon Nadd who established a Dark Side theocracy. The Naddists expelled dissidents into the wilds of Onderon who established a new civilization known as the Beast Riders. In 4000 BBY, a Jedi mission led by Ulic Qel-Droma teamed up with the Beast Riders to overthrow the Naddists; ending the centuries-long Beast Wars.
In 3996 BBY during the Great Sith War, Mandalorian forces invaded Onderon but were decimated by Republic reinforcements while their leader Mandalore the Indomitable met his demise on the jungle moon of Dxun. For much of the Jedi Civil War, the Selkath of Manaan maintained a state of neutrality and supplied the therapeutic kolto to both the Republic and Darth Malak's Sith Empire. With the decline of the kolto market and the destruction of its surface cities during the Great Galactic War, Manaan slipped into primitive decline.
In 22 BBY, several Inner Rim worlds including the Givin homeworld of Yag'Dhul joined Count Dooku's Confederacy of Independent Systems during the Separatist Crisis. The Gotal homeworld of Antar 4 was the site of fighting between the pro-Republic Antarian Rangers and the Separatists. The fallout from the deployment of the electromagnetic pulse weapon that incapacitated many Gotals prompted thousands of worlds to secede and join the Confederacy. During the Clone Wars in 21 BBY, the Fourth Constitutional Amendment gave Republic worlds in the Core, Colonies, and Inner Rim more voting power than worlds in the Expansion Region and beyond.
During the reign of Palpatine, the Galactic Empire ruthlessly controlled the Inner Rim. Rather than rebel, many residents chose to flee to the Outer Rim Territories. In 6 ABY, the Dark Jedi warlord Shadowspawn waged a dogged and savage campaign against New Republic forces on Mindor. In 7 ABY, Thyferra was the site of fighting between Ysanne Isard's Imperial faction and Rogue Squadron over control of the production and supply of therapeutic bacta. Due to the entrenched Imperial presence, much of the region was held by the Empire until as late as 9 ABY. Subsequently, many Inner Rimmers later resented the New Republic's sluggishness in liberating the region. Many worlds, despite joining the New Republic, were openly afraid that the government was not strong enough to maintain power.
Their concerns were realized following the return of Palpatine in 10 ABY during Operation Shadow Hand. Following the deployment of the world-destroying Galaxy Gun against several Republic targets, the clone incarnation of Palpatine reclaimed most of the Inner Rim. With the final demise of Palpatine during the Battle of Onderon in 11 ABY, much of the region quickly fell back under the New Republic's control. By the end of the Galactic Civil War in 19 ABY, the remnants of the Empire had been driven into eight barren sectors in the Outer Rim.
During the Yuuzhan Vong War, the Ailon Nova Guard joined forces with the Yuuzhan Vong invaders in conquering several Inner Rim worlds including Cona, Manaan and Zeltros. However, the invaders suffered a substantial setback at the Battle of Yag'Dhul. Following the cessation of conflict in 30 ABY, the Republic's successor state the Galactic Federation of Free Alliances temporarily established its capital on Denon until reconstruction concluded on the devastated galactic capital Coruscant.