Pralaya , in Hindu cosmology , is a period of time of the cycle of existence of the planets where activity does not occur. It lasts, according to computations of the Brahmans, 4,320,000,000 years. The period of activity, Manvantara, has the same duration.

Taking 360 Manvantaras and equal number of Pralayas, one "Year of Brahman" is gotten. The duration of 100 "Years of Brahman" forms a "Life of Brahman", call of Mahamanvantara , also lasting in total 311,040,000,000,000 years. This is, according to Blavatsky, the period of activity of the cosmos, following itself a period of inactivity, Mahapralaya, of equal duration.