It goes back ever further, Java 1.2 was marketed by Sun as "Java 2".

https://web.archive.org/web/19991010063140/http://java.sun.c...

That was somewhat different from the way the internal stuff was numbered. You'd still see "1.5" and "1.6" everywhere when you asked the JVM for it's version. 8 was when the JVM started matching the marketing (IIRC, might have been 9).