Kalpa

''Some would say that all things must end, so that the next can come to pass. Perhaps this world is simply the Egg of the next kalpa? - Paarthurnax''

A kalpa is a period of time over which the world of the Elder Scrolls exists. Some sources indicate that at the end of the kalpa, time resets to a new Dawn Age.

Due to the age reseting at a new Dawn Era, the creation of Mundus can emerge in different ways each kalpa, with different et'Ada playing different roles. For example, Vivec recounts Molag Bal being prince of the Dreugh in what may be a previous kalpa, and Umaril's father is claimed to be god of the world river in a previous kalpa.

This is apparently possible because the Leaper Demon King hides parts of the world from Alduin each cycle, which are then stuck into the world by the Greedy Man, who is likely to be Lorkhan.

Trivia
"Kalpa" is a Sanskrit term for eon, and has specific meanings (and different lengths) in Hinduism and Buddhism.