Order 66

Order 66 is an existing event from Legends.

Palpatine used the energies released by the mass death of Jedi to erase most of the memory of the Jedi Order from the galaxy. As a result, even people who lived through the Clone Wars and were familiar with the exploits of the Jedi would later think of them as a "hokey ancient religion," even though only two decades had passed since the days of their greatest prominence.