Related issue: tidyverse/lubridate#2
Summary: If you are wondering about how to do deal with BCE dates in R, especially with the Lubridate R package (v1.7.9), or to implement those within the Lubridate package, here are some thoughts about problems caused by a phantom year zero.
If anyone is considering dealing with "before common era" dates in lubridate, be aware that Year zero doesn't exist (for historians I mean, there is Year -1 and then Year 1, see for example the Wikipedia chronology – also note that's for the Julian calendar, that could have minor conflicts with the Gregorian calendar we use nowadays; you would find more details about this on Wikipedia), and that can cause a few problems.