Manvantara is a period of time in Hinduism. The period of
time is found mainly in Harivamsa and certain Puranas. The concept of Manvantara
is not widely mentioned in the Epics – Mahabharata and Ramayana.
A Manvantara is said to consist of a total of just over 71
Mahayugas. There is no exact count as it is given differently in different
scriptures.
Each Mahayuga lasts for a total of 12000 Divine years or 4,320,000 human years.
There are 14 Manvantaras – this is equal to 1000 Maha Yugas
or 4,320,000,000 human years. It is the measure of a Kalpa or day of brahma.
At the end of each kalpa there is the dissolution of the
entire three worlds.