use strict;
use warnings;

use Data::Dumper;

my %continents;
while ( <DATA> )
{
    chomp;
    my( $continent, $country ) = split m{:};
    push @{ $continents{ $continent } }, $country;
}

print Data::Dumper->Dumpxs(
   [ \ %continents ],
   [ qw{ *continents } ]
   );

__DATA__
Europe:Germany
Europe:France
Asia:India
Europe:Italy
Asia:Japan
Asia:Indonesia