To answer your question there are metal bands from the following countries (courtesy of MA):
Afghanistan
Albania
Algeria
Andorra
Argentina
Armenia
Australia
Austria
Bahrain
Bangladesh
Belarus
Belgium
Belize
Bolivia
Bosnia and Herzegovina
Botswana
Brazil
British Virgin Islands
Brunei
Bulgaria
Canada
Chile
China
Colombia
Costa Rica
Croatia
Cuba
Cyprus
Czech Republic
Denmark
Dominican Republic
Ecuador
Egypt
El Salvador
Estonia
Faroe Islands
Finland
France
Georgia
Germany
Gibraltar
Greece
Greenland
Guam
Guatemala
Guyana
Honduras
Hong Kong
Hungary
Iceland
India
Indonesia
Iran
Iraq
Ireland
Israel
Italy
Japan
Jordan
Kazakhstan
Korea, South
Kuwait
Kyrgyzstan
Laos
Latvia
Lebanon
Libya
Liechtenstein
Lithuania
Luxembourg
Macedonia
Madagascar
Malaysia
Malta
Martinique
Mexico
Moldova
Monaco
Mongolia
Morocco
Namibia
Nepal
Netherlands
New Caledonia
New Zealand
Nicaragua
Norway
Pakistan
Panama
Paraguay
Peru
Philippines
Poland
Portugal
Puerto Rico
Qatar
Reunion
Romania
Russia
San Marino
Saudi Arabia
Serbia and Montenegro
Singapore
Slovakia
Slovenia
South Africa
Spain
Sri Lanka
Sweden
Switzerland
Syria
Taiwan
Tajikistan
Tanzania
Thailand
Trinidad and Tobago
Tunisia
Turkey
Turkmenistan
Ukraine
United Arab Emirates
United Kingdom
United States of America
Uruguay
Uzbekistan
Venezuela
Vietnam
Zimbabwe
So yeah, it's international.