Oh I can imagine that is quite a bit of a shock due to the difference in when public records were made. While many of the Southern States were around during the 1600-1700s, I don't think that any of them started requiring the keeping of vital records until more modern times, with the exception of Marriage Records. Marriage records, usually in the forms of Marriage Bonds, were in place from 1741-1868, which were basically a promise to marry, filed with the County clerks' offices; but even a lot of those have been lost through time, with some Counties having no records due to courthouse fires or other incidents that occurred during the Revolutionary War, War of 1812, and Civil War, where records may have been destroyed.
A few Delayed Birth Records were filed in later years that cover people born prior to 1913, usually by people who needed an official birth record for things like Social Security, but those are only a very small fraction. And while 1913 was the date that the State started requiring the registering of births, it still wasn't fully complied with by everybody for many years, there are many individuals born in various locations where no birth records can be found.