There is no Views relationship to civicrm_country nor civicrm_worldregions. How to create a view counting number of contacts from a region?
As of CiviCRM Entity 2.0-beta8 the Views relationships to Country and World Region have been made available. You must install the CiviCRM Entity Views Extras submodule.
CiviCRM Entity can be downloaded here: https://www.drupal.org/project/civicrm_entity