the leavers chapter of human history ended 10,000 years ago in the fertile crescent. what happened to end the reign of the leavers and began the reign of the takers

In essence, the Leavers either became Takers (civilized farmers) or continued to be Leavers. Leavers didn't move forward and set aside progression. According to the text, Leavers still exist but live in the past because they don't understand that their part of history has ended. (Page 42)