What was linux/unix time standard before inventing epoch? [closed]

As in the title, I was looking for, but hadn't found. How were time stored and processed before epoch standardizing in 2000?

UNIX epoch began 1970-01-01, a date approximately when it was named such and escaped Bell Labs. NTP era 0 has been 1900-01-01 since at least v0 circa 1985. These and other time scales were well established on UNIX systems, before Linus sent the "just a hobby" email about Linux on 1991-08-25.

Linux 0.01 does not have many time functions in the kernel. Mostly converting real time clock time values into a usable integer so the boot time can be established. Presumably UNIX epoch, given the "- 70" done to the year, and the comments wondering about the choice of 1970.

See man 7 time for a list of time functions on a modern Linux system.