Mahayugas

Mahayugas are cycles of four ages in Hindu cosmology: Satya Yuga, Treta Yuga, Dvapara Yuga, and Kali Yuga. A complete mahayuga lasts 4,320,000 years, divided into the four ages in this order: Satya Yuga lasts 1,728,000 years; Treta Yuga lasts 1,296,000 years; Dvapara Yuga lasts 864,000 years; and Kali Yuga lasts 432,000 years.

In these cycles, virtue and dharma are said to decline from one age to the next. Satya Yuga is described as the age of righteousness and harmony, with moral order at its peak. In Treta Yuga, righteousness begins to waver, and by Kali Yuga it is said to be at its lowest. The transitions between ages are marked by gradual changes in human conduct, longevity, and the overall pace of life, according to scriptural descriptions.

Mahayugas do not occur in isolation. They form part of larger cosmological time frames in Hindu thought. A day of Brahma, the creator deity, lasts 4.32 billion years and consists of 1,000 mahayugas (and the corresponding nights of equal length). A kalpa, the full day of Brahma, is followed by a night of equal duration, and together these cycles are embedded within even larger cycles that include multiple manvantaras and periods of dissolution.

The concept of mahayugas appears in various Hindu scriptures, including the Puranas and epics, where these vast time scales are used to describe cosmic creation, preservation, and renewal. Some traditions note variations in numerical values, but the 4.32-million-year mahayuga framework remains the most commonly cited standard.