Yuga, in Hinduism, is the Sanskrit term for an “age,” meaning one of the four periods in which the world cycle is divided: (i) krta (or satya)-yuga, the golden age when there is unity (one god, one veda, one ritual), in which the varnas perform their roles without oppression or envy; (ii) treat-yuga, when righteousness begins to decline by a quarter and sacrifice begins; (iii) dvapara-yuga, when righteousness again declines by a quarter, the Vedas split into four and few study them; (iv) kali-yuga, further decline by a quarter, when disease, despair, and conflict dominate. At present the world is considered to be in kali-yuga, which began 3102 BC, so there should be no optimism concerning general future prospects. The duration of each yuga (with each in succession reducing by a quarter to reflect the decline in righteousness) is: (i) 1,728,000 human years; (ii) 1,296,000; (iii) 864,000; (iv) 432,000. The total 4,320,000 = one maha-yuga, or “great age”; 2,000 maha-yugas = one day and one night in the life of Brahma. A.G.H.
Bowker, John, The Oxford Dictionary of World Religions, New York, Oxford University Press, 1997, p. 1061