Matsya Purana — Measures of Time: Caturyuga Computation
नव यानि सहस्राणि वर्षाणां मानुषाणि च वर्षाणि नवतिश्चैव ध्रुवसंवत्सरः स्मृतः //
nava yāni sahasrāṇi varṣāṇāṃ mānuṣāṇi ca varṣāṇi navatiścaiva dhruvasaṃvatsaraḥ smṛtaḥ //
Nine thousand human years—together with a further ninety years—are traditionally known as the Dhruva-year (dhruva-saṃvatsara).
Indirectly, it supports Pralaya doctrine by defining precise cosmic time-units: dissolution and re-creation are described as occurring after vast, measured cycles rather than random events.
By emphasizing fixed measures of time, it underpins dharma-practice that depends on calendrical reckoning—vows, taxes, rites, festivals, and governance schedules are ideally aligned with recognized time-units.
The verse itself is chronological, but such time-units are used to time consecrations (pratiṣṭhā), seasonal rites, and other ritual calendars that also guide temple and household ceremonial planning.