A similar entry appears in the Wheel of Time Companion confirming the information available in the main story arc.
Author: Atarah al'Norahn
Oman Dahar was one of the nations of the Free Era. It was located in the western part of the Westlands. To the northwest was Abayan, with Indrahar to the north, Oburun to the northeast, Masenashar to the east, Farashelle to the southeast and Darmovan to the southwest. Eventually, this area of land became what is now part of Arad Doman and the Mountains of Mist.
By FY 963, Oman Dahar had fallen to Hawkwing.
(Reference: The World of Robert Jordan's "The Wheel of Time")