By default, the Ubercart module provided a list of countries where you can add or remove them in Adminster -> Store administration -> Configuration -> Country settings.

If you cannot find the countries u need, there is an additional list of countries in the Ubercart website. Add them to your Drupal site as follow.

1. Download the addition countries list @ here

2. Extract the downloaded file in <drupal_root>/sites/all/modules/ubercart/uc_store/countries.

3. You will now find more countries @ Adminster -> Store administration -> Configuration -> Country settings.

Reference: Adding Country Codes to Drupal Ubercart