my $region1;
my $region2;
.
.
.
foreach $region1 (@region_list) {
   foreach $region2 (@region_list) {
      ...
   }
}

##</code><code>##

foreach my $region1 (@region_list) {
   foreach my $region2 (@region_list) {
      ...
   }
}

##</code><code>##

my $region;
my $region1;
.
.
.
foreach $region (@region_list) {
   ...
}
.
.
.
foreach $region1 (@region_list) {
   ...
}

##</code><code>##

foreach my $region (@region_list) {
   ...
}
.
.
.
foreach my $region (@region_list) {
   ...
}