Bhagavatapurana 5.16.8

5.16.8

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uttarottareṇelāvṛtaṃ nīlaḥ śvetaḥ śṛṅgavān iti trayo ramyaka-hiraṇmaya-kurūṇāṃ varṣāṇāṃ maryādā-girayaḥ prāg-āyatā ubhayataḥ kṣārodāvadhayo dvi-sahasra-pṛthava ekaikaśaḥ pūrvasmāt pūrvasmād uttara uttaro daśāṃśādhikāṃśena dairghya eva hrasanti //

8. On the northern side adjoining Ilavrita are three mountain ranges, called Neela, Sweta and Sringavan, the boundary mountains between the Varshas of Ramyaka, Hiranmaya and Kuru, running east and west both ways, terminated by the salt sea, each two thousand yojanas in extent, and every exterior range being shorter in length by a little over a tenth of the next interior range.