Matsya Purana — Cosmography of Śākadvīpa and Successive Dvīpas: Mountains
तस्यापरेण सुमहाञ् श्यामो नाम महागिरिः यत्र श्यामत्वमापन्नाः प्रजाः पूर्वमिमाः किल //
tasyāpareṇa sumahāñ śyāmo nāma mahāgiriḥ yatra śyāmatvamāpannāḥ prajāḥ pūrvamimāḥ kila //
To the west of that region stands a very great mountain named Śyāma; there, it is said, these peoples of old became dark-complexioned.
This verse is not about pralaya; it belongs to a geographic/ethnographic description, locating a mountain (Śyāma) and attributing an old tradition about the complexion change of peoples associated with that region.
Directly, it does not prescribe rājadharma or gṛhastha-dharma; indirectly, such geographic notes support a king’s knowledge of lands and peoples (deśa-jñāna) used in governance, travel, and administration described elsewhere in Purāṇic literature.
No explicit Vāstu or ritual rule is stated; the verse functions as a toponymic landmark (a named mountain) that could serve as a traditional geographic reference for tīrtha-travel or regional mapping in Purāṇic contexts.