Matsya Purana — Cosmography of Jambūdvīpa: Varṣas
पार्श्वमुत्तरतस्तस्य रक्तवर्णं स्वभावतः तेनास्य क्षत्रभावः स्याद् इति वर्णाः प्रकीर्तिताः //
pārśvamuttaratastasya raktavarṇaṃ svabhāvataḥ tenāsya kṣatrabhāvaḥ syād iti varṇāḥ prakīrtitāḥ //
On his northern side, the flank is naturally red in color; therefore it is said that a Kṣatriya disposition arises in him—thus the varṇas are described.
This verse does not discuss pralaya; it focuses on dharma-oriented classification, describing a bodily sign associated with Kṣatriya disposition.
By linking a “Kṣatra-bhāva” (warrior/royal temperament) to recognizable traits, the text frames kingship and governance as a dharmic role rooted in qualities—implying that protection, rule, and disciplined strength are appropriate where Kṣatriya nature is present.
No Vāstu or ritual procedure is stated here; the verse is part of a dharma/varṇa-lakṣaṇa discussion rather than temple architecture rules.