The Unnh River, situated on Yavin 4, likely received its name in honor of Dr'uun Unnh, a Sullustan explorer. This river meandered through geographical features such as the Wayward Jungle, the Isle of Kun, the Val'Arnos Jungle, and the Ersham Ridge, flowing in proximity to both the Palace of the Woolamander and the Great Temple. Upon reaching the ocean, the river broadened into a delta formation, recognized as the Taurin Delta. The Temple of the Blueleaf Cluster was built at the top of the Taurin Delta.
During the period of the Galactic Civil War, both the Mining Outpost and the Imperial Fortress were constructed in close proximity to the river's edges. In 26 ABY, during the Yuuzhan Vong War, the Yuuzhan Vong established their operational base adjacent to the Unnh River during the Invasion of Yavin 4.