app.js

define([
    'marionette',
    'modules/login',
    'modules/main'
], function (Marionette, loginModule, mainModule) {
    "use strict";

    var app = new Marionette.Application();

    app.addRegions({canvas: '#canvas'});
    app.module('login', loginModule);
    app.module('main', mainModule);

    return app;
});

main.js

require([                                                                                                                                                                                                                                     
    'app',
    'backbone',
    'marionette'
], function (app, Backbone, Marionette) {
    "use strict";

    Marionette.Renderer.render = function (template, data) {
        return template(data);
    };  

    app.start();
    // Wrap in auth dance.
    app.module('login').start();
    Backbone.history.start();
});

modules-login.js

define([                                                                                                                                                                                                                                      
    'routers/login',
    'controllers/login'
], function (LoginRouter, LoginController) {
    "use strict";

    return {
        startWithParent: false,
        define: function () {
            this.addInitializer(function () {
                new LoginRouter({
                    controller: new LoginController({
                        region: this.config.app.canvas
                    })  
                }); 
            }); 
        }   
    };  
});

modules-main.js

define([                                                                                                                                                                                                                                      
    'routers/index',
    'controllers/index'
], function (IndexRouter, IndexController) {
    "use strict";

    return {
        startWithParent: false,
        define: function () {
            this.addInitializer(function () {
                new IndexRouter({
                    controller: new IndexController({
                        region: this.config.app.canvas
                    })  
                }); 
            }); 
        }   
    };  
});