from time immemorial

• 自古以来,无法记忆的过去

from time immemorial的用法和样例：

例句

1. That practice has been going on time out of mind.
   这种做法自古以来一直沿用。
2. The hostility between the two nationalities dates from ancient time.
   这两个民族之间自古以来就存在着一种敌对状态。