gistfile1.js

masterObj = {}
_.extend( masterObj, Backbone.events);
masterObj.registry = {
  models:[]
  register:function(name,model){
   this.models[name] = model;
  },
  get:function(name){
   if(this.models[name]) return this.models[name];
   return false;
  }
}
var model1=Backbone.Model.extend({
  initialize:function(){
   var model2 = masterObj.registry.get("model2"); // this could also be a promise if the model isnt ready at this time
    if (model2){
     model2.bind("change:property",function(){
      // change model1 properties
     });
  }
});
var model2 = Backbone.Model.extend({
  intitalize:function(){
    
  }
});

var view = Backbone.View.extend({
  model:model2,
  events:{
   "click elm" : "changeThis"
  },
  initialize:function(){
   masterObj.registery.register( "model2", this.model);

  },
  changeThis:function(){
   this.model.set({"property":1});
  }
});