Genesis 6:3 King James Version (KJV)

And the Lord said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years.

120 = MOED Apponited Time and in this context holy years which is 50 years or Jubilee.  50 x 120 years = 6,000 years. Mankind has been on this planet for 6,000 years. We are now waiting any day now for our rest Redemption.