This is an example of a pastoral leasehold run. It's the Obella Holding [NRS 8352 lease #709] which was situated south of Dubbo, part of the Central Land Division.
The Obella Holding was a pastoral area of 33,736 acres, leased to Silas Harding. Silas also had the pastoral holding of Tabraton West, a run of 5080 acres.
The map was most likely drawn up when Silas applied for an occupation licence, some time around 1885-90. It includes such features as the Chain of Ponds Run, Little River and Herveys Ranges.