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We are very certain that Lord Rama, Lord Krishna and other Avatars took place. But the question remains is why are we not able to clearly find the traces of these? Is it that their incarnations were in previous Mahayuga or previous manvantara or previous Kalpa or Brahma lifespan? Please can anyone help me in knowing the events in the life of Brahma from time of his life span till date of our age. Relevant references from various Puranas will be helpful.