Matsya Purana — Yuga Durations
*मत्स्य उवाच चत्वार्याहुः सहस्राणि वर्षाणां तु कृतं युगम् तस्य तावच्छती संध्या द्विगुणा रविनन्दन //
*matsya uvāca catvāryāhuḥ sahasrāṇi varṣāṇāṃ tu kṛtaṃ yugam tasya tāvacchatī saṃdhyā dviguṇā ravinandana //
Matsya said: The sages declare that the Kṛta Yuga consists of four thousand years. Its twilight period (sandhyā) is of that many hundreds of years, and the concluding twilight (sandhyāṃśa) is twice that, O descendant of the Sun.
It gives the Purāṇic framework of cosmic time (yuga lengths and twilight junctions), which is the calendrical basis used to describe recurring cycles of creation, maintenance, and dissolution across vast epochs.
By defining the Kṛta Yuga as a distinct moral-temporal phase, it implies that Dharma and social duties are understood in relation to the yuga—kings and householders are expected to align conduct with the prevailing age’s standards of righteousness and discipline.
No direct Vāstu or temple rule is stated; the practical ritual takeaway is calendrical—yuga and sandhyā concepts underpin Purāṇic timing and sacred chronology used to contextualize rites, vows, and traditional reckonings of auspicious periods.