React From Zero
A simple (99% ES2015 less) tutorial for React
Everything runs in the browser without a manual pre-compilation.
No need for Webpack, but I would recommend looking into it. It helped me to get rid of much Grunt/Gulp code in my projects.
I saw a increase in stars after posting this to HN yesterday, so I decided to write some more lessons.
If anyone has wishes/ideas for lessons, write an issue :)