If you're interested in some of the milestones along the way and the context of web programming back in 2004 and 2005 when Rails came out, I made a timeline for my talk at RailsConf this year: http://www.recursion.org/looking-backward/

It was fun to research all this stuff. It's interesting to see how far back some of this stuff goes. For example, Rails gets much of its power from Ruby's flexibility. Ruby is heavily inspired by Smalltalk. The first research version of Smalltalk came out in 1972! The MVC pattern was also first developed at PARC, back in 1978.