The eastern barrier, a formidable defensive structure, functioned as a colossal wall on the planet Geonosis. During the Second Battle of Geonosis, after their gunships were downed, Jedi General Anakin Skywalker, Jedi Commander Ahsoka Tano, and soldiers from the 501st Legion, including Clone Captain Rex, stumbled upon this barrier as they battled towards the main staging location at Point Rain. Tano had previously brought the wall to Skywalker's attention in a pre-combat briefing, but the Jedi Knight disregarded the likelihood of them getting anywhere near it.
Carrying explosives to destroy the wall, Skywalker and Tano made their way to its summit. Following the elimination of all defending battle droids, with support from the clone troopers below and after Rex joined them, the two Jedi placed the explosives inside the wall through a trapdoor opened by a battle droid. They then used telekinesis to lower Rex from the wall and leaped off themselves just before the detonation. Upon landing, Skywalker and Tano employed telekinesis to catch Rex before he reached the ground, and the team advanced through the remnants of the eastern barrier, continuing their journey to Point Rain.
The first appearance of the eastern barrier was in the Star Wars: The Clone Wars season 2 episode titled "Landing at Point Rain," which was broadcast in 2009.