Unix was developed back in the days when Microsoft didn't even exist.
Linux is not Unix, only based upon the technology Unix is built on. Linux is what you can call.. kind of a clone.
Linus Torvalds created Linux cause he wanted a Unix like OS on a PC compatible computer. You can't put Unix on a regular PC. There are free versions of Unix out there, but the majority of them you still buy.
Here is a link about Unix.. has some other good links covering the history of Unix.
http://perso.wanadoo.fr/levenez/unix/