The Jimbern Regions were areas of land on the planet Acamar III. These regions were bordered by the Niwray Border and the Jamholt Region. Portions of these regions were claimed by Clan Tralesta.
In 2286, after the Niwray Border disputes escalated into full war between the Clans Lornak and Tralesta, the former launched brutal reprisals against the latter in these regions. Tralesta clan elders attempted to mobilize defenses, but as they hadn't prepared adequately for the scale of these reprisals, the village of Lornbiv was sacked by the Lornak. (TNG: "The Vengeance Factor")
These regions were mentioned in the records of the Tralesta Massacre, which were accessible to the crew of the USS Enterprise-D via the Acamarian planetary database.