Build your own version of Backbone.
git clone git://github.com/Acconut/backbone-build.git
cd backbone-build
npm install
build
# All information you need
build -i router,sync -o mybackbone.js -m
# Only include router and sync
# and output is inside mybackbone.js
# and minify all.
Current Backbone version: 1.0.0
Note: Your build doesn't include Underscore.js.