Matsya Purana — Solar–Lunar Motions
तथा शतसहस्राणाम् एकोनाशीतिर् उच्यते सप्तद्वीपसमुद्रायाः पृथिव्याः स तु विस्तरः //
tathā śatasahasrāṇām ekonāśītir ucyate saptadvīpasamudrāyāḥ pṛthivyāḥ sa tu vistaraḥ //
Likewise, it is stated to be eighty-one hundred-thousands (i.e., 8,100,000) in measure—this is the expanse of the Earth together with its seven continents and oceans.
This verse is not about Pralaya; it gives a cosmographic measurement, stating the total expanse of the Earth as conceived with seven continents and surrounding oceans.
Indirectly, it supports the Purana’s ideal of informed rulership and ordered life: knowing the world’s divisions and measures is part of the broader framework of dharma, administration, and pilgrimage-oriented geography.
No direct Vastu or ritual rule is stated; however, such cosmographic measures often underpin sacred mapping (mandala thinking) used in temple orientation and ritual geography in later applied traditions.