Matsya Purana — Division of Bhārata-varṣa
आयतस्तु कुमारीतो गङ्गायाः प्रवहावधिः तिर्यगूर्ध्वं तु विस्तीर्णः सहस्राणि दशैव तु //
āyatastu kumārīto gaṅgāyāḥ pravahāvadhiḥ tiryagūrdhvaṃ tu vistīrṇaḥ sahasrāṇi daśaiva tu //
From the region of Kumārī onward extends the limit of the Gaṅgā’s flowing course; and its spread—horizontally and upward—is said to be exactly ten thousand yojanas.
This verse is not describing Pralaya; it gives a cosmographic/sacred-geographic measurement of the Gaṅgā’s flowing extent and its vast spatial spread.
By locating and quantifying sacred geography, the text supports dharmic duties such as tīrtha-yātrā, patronage of ghāṭas/temples, and orderly settlement planning near sacred waters—activities often undertaken or sponsored by kings and householders.
The emphasis on measured extent aligns with Vāstu-style thinking: sacred sites and riverfront ritual spaces (ghāṭas, temples, pilgrimage infrastructure) are ideally planned with attention to canonical dimensions and the perceived sacred “field” of the river.