Markandeyapurana 46.28

46.28

tretā trīṇi sahasrāṇi divyābdānāṃ śatatrayam /
tatsandhyā tatsamā caiva sandhyāṃśaśca tathāvidhaḥ //

Now the Kṛta age is said to have contained four thousand years; its commencing twilight was four hundred years, and the closing twilight was of the same duration. The Tretā age was three thousand divine years; and three hundred years was its commencing twilight, which was indeed of that duration, and its closing twilight was of the same duration. The Dvāpara age was two thousand years; and its commencing twilight is declared to have been two hundred years, and its closing twilight was two hundred years. The Kali age is a thousand divine years, O brahman; two hundreds of years are called its commencing and closing twilights;