Skandapurana 16.319.49

16.319.49

pūrve tu śāṃkarī cā''ryā paścime nyaṃkumatyapi ..
uttare kanakanaṃdā dakṣiṇe sāgarāvadhiḥ ..
etadaṃtaramāsādya deśo nagnaharaḥ smṛtaḥ .. 49 ..

To the east is the noble Śāṃkarī, and to the west the Nyaṅkumatī, / to the north the Kanakanandā, and to the south the ocean is its boundary; / reaching this intermediate space, the region is remembered as Nagnahara.