कृतं त्रेता द्वापरं च कलिश्चेति चतुर्युगम् ।
दिव्यैर्द्वादशभिर्वर्षै: सावधानं निरूपितम् ॥ १८ ॥
kṛtaṁ tretā dvāparaṁ ca
kaliś ceti catur-yugam
divyair dvādaśabhir varṣaiḥ
maitreyaḥ uvāca — Maitreya said; kṛtam — the age of Satya; tretā — the age of Tretā; dvāparam — the age of Dvāpara; ca — also; kaliḥ — the Age of Kali; ca — and; iti — thus; catuḥ-yugam — four millenniums; divyaiḥ — of the demigods; dvādaśabhiḥ — twelve; varṣaiḥ — thousands of years; sa-avadhānam — approximately; nirūpitam — ascertained.
Maitreya said: O Vidura, the four millenniums are called the Satya-, Tretā-, Dvāpara- and Kali-yuga. The aggregate number of years of all of these combined is equal to twelve thousand years of the demigods.
The years of the demigods are equal to 360 years of humankind. As will be clarified in the subsequent verses, 12,000 of the demigods’ years, including the transitional periods which are called yuga-sandhyās, comprise the total of the aforementioned four millenniums. Thus the aggregate of the above-mentioned four millenniums is 4,320,000 years.