When you say something dates back to a particular time, you mean that thing started or was created in that time. When you say something dates back for a particular length of time, then you mean it has existed for that amount of time.
What does date back to mean?
: to have been made in or to have come into being in (a certain time in the past) They found jewelry dating back to the 1700s.
How do you say dates back?
revert to; date back to; stem from; return; go down; go back to; go back.
What do you mean by dead?
Dead, deceased, extinct, lifeless refer to something that does not have or appear to have life. Dead is usually applied to something that had life but from which life is now gone: dead trees. Deceased, a more formal word than dead, is applied to human beings who no longer have life: a deceased member of the church.