amd-require.html

<title>backbone-nested amd require</title>

<script data-main="amd-require.js" src="../vendor/requirejs/require.js"></script>

amd-require.js

require.config({
  baseUrl: '..',
  paths: {
    underscore: 'vendor/lodash/dist/lodash.underscore',
    jquery: 'vendor/jquery/jquery',
    backbone: 'vendor/backbone/backbone',
    'backbone-nested': 'backbone-nested'
  }
});

require(['backbone', 'backbone-nested'], function(Backbone, _) {
  console.log(Backbone.NestedModel);
});