Matsya Purana — Division of Bhārata-varṣa
तैर्विमिश्रा जानपदा आर्या म्लेच्छाश्च सर्वतः पिबन्ति बहुला नद्यो गङ्गा सिन्धुः सरस्वती //
tairvimiśrā jānapadā āryā mlecchāśca sarvataḥ pibanti bahulā nadyo gaṅgā sindhuḥ sarasvatī //
With them, the provinces are intermingled on every side—both Āryas and Mlecchas everywhere. Many rivers flow there, and people drink their waters: the Gaṅgā, the Sindhu, and the Sarasvatī.
This verse is not about Pralaya; it belongs to a geographic-ethnographic description, emphasizing the intermingling of peoples and the life-sustaining role of major rivers.
By noting mixed populations (Ārya and Mleccha) and shared dependence on rivers, it implies governance and household life must account for diverse communities and protect river-water access—key to prosperity, agriculture, and public welfare.
No direct Vāstu rule is stated, but the prominence of Gaṅgā–Sindhu–Sarasvatī highlights river proximity as ritually auspicious and practically vital—often guiding site-selection for settlements, ghāṭas, and temples in related Purāṇic and Vāstu contexts.