Yuga

In Hinduism, the world goes through 1000 yuga-cycles during one kalpa (a day of Brahma).

There are four parts to a yuga-cycle, representing deterioration. First is Krita yuga or the age of perfection, and then treta yuga, followed by dvapara, after that Krishna was made incarnate, and finally the fourth and final yuga, kali happens, where creation is the most deteriorated (yuga is from a game of dice).