Is it improtant for a society to have knowledge about its past?

I think it's important.
A society's past is valueble for us to learn vacariously about the experience.For example,we can learn how to face problem through learning Red Army or learning from Chairman Mao.We can learn how to cover Economic crisis through learning the past Economic crisises.
Also,a country forms its style though many years.Our cultrue and manner based on the society's past.For example,Pasting couplets .
All in all,a society nowadays based on past days,its past is no doubt important.