since time immemorial
US /sɪns taɪm ɪmɪˈmɔːriəl/
UK /sɪns taɪm ɪmɪˈmɔːriəl/
1.
for a very long time, for a period longer than anyone can remember
:
•
The tradition has been passed down since time immemorial.
•
People have been fishing in this river since time immemorial.