Matsya Purana — Cosmography of Śākadvīpa and Successive Dvīpas: Mountains
एतान्यपि विशिष्टानि सप्त सप्त पृथक्पृथक् वर्षाणि पर्वताश्चैव नदीस्तेषु निबोधत //
etānyapi viśiṣṭāni sapta sapta pṛthakpṛthak varṣāṇi parvatāścaiva nadīsteṣu nibodhata //
Learn also of these distinguished sets—seven and seven, each separately: the regions (varṣas), the mountains, and the rivers that belong to them.
This verse is not about Pralaya; it signals a cosmographic listing—how the world is mapped into sets of seven regions, with their associated mountains and rivers.
Indirectly, it frames dharmic governance and ritual life within a sacred geography—knowing regions, rivers, and mountains supports pilgrimage, boundary-setting, and the king’s role as protector of the land’s ordered divisions.
No explicit Vāstu rule is stated here, but such river–mountain mappings commonly ground tīrtha-rituals and site sanctity—key inputs later used when choosing auspicious locales for temples and settlements.