The Harrin sector was situated within the Trailing Sectors region of the Inner Rim. It encompassed the Harrin system, whose primary planet shared the name Harrin. The system of Harrin was positioned along the super-hyperroute called the Corellian Trade Spine, and it also marked the termination point for the Harrin Trade Corridor.
Exploration of the space in the vicinity of the Harrin system took place across a period spanning from 20,000 BBY to 15,000 BBY. Sometime between 17,000 BBY and 12,000 BBY, the system integrated into the Galactic Republic. By the year 12,000 BBY, the planet was located within the Corellian Hegemony, an area under the economic influence of the Core Worlds planet Corellia.
During the Clone Wars, which occurred from 22 BBY to 19 BBY, the Harrin system fell within the boundaries of the Confederacy of Independent Systems. By 17 BBY, the Galactic Empire had control over the system's territory.
The sector known as Harrin was first presented in the StarWars.com Online Companion for The Essential Atlas, a reference book from 2009 authored by Daniel Wallace and Jason Fry.