It was deleted from the default build of the timezone files but remains in the source tree; patches are accepted.

Choices have to be made for usefulness vs completeness vs size as it's quite likely that at least one and perhaps multiple copies of the database are present on any system out there running code in C that needs to know what time it is in human terms.

But if you're a packrat, you can include the extras in your build of the timezone data by setting PACKRATDATA=backzone during the build.

It wasn't! See https://github.com/eggert/tz/blob/main/asia