I suspect that you really want to store the coordinates as a four-element array as opposed to a 4-dimension array. The following might serve as an executable example of what you want:

use strict;
use Data::Dumper;

my %zones;
while (<DATA>) {
    chomp;
    my ($zone, $a1, $a2, $b1, $b2) = 
        $_ =~ /(\w+) = (\d+),(\d+),(\d+),(\d+)/;
    #append an anonymous (coordinate) array on to the
    #anonymouse array that is the value for each hash
    #key in %zones hash.
    push @{$zones{$zone}}, [$a1, $a2, $b1, $b2];
}
print Dumper(%zones);

__DATA__
B1 = 11,21,3,59
B2 = 1,23,7,51
B1 = 9,2,11,9
B2 = 1,23,7,59
B3 = 3,92,12,13
B1 = 2,2,18,50
[download]

Cool,thats what I'm lookin' for

my %zones;
$zones{B1} = [1,23,7,59];
my @this_coord = (5, 7);
my ($x, $y) = @this_coord;
while (my ($zone, $rng) = each %zones) {
  print "Zone is $zone\n" if $$rng[0]<=$x && $$rng[1] >=$x
      && $$rng[2]<=$y && $$rng[3]>=$y;
}
__OUTPUT__
Zone is B1
[download]

my ($coord1, $coord2);
$hash{$coord1 . "," . $coord2} = 'value';
[download]

Actually, perl has a built-in facility for this... if you simply say:

$hash{$coord1,$coord2} = $value;
[download]

then perl automatically constructs a hash key as:

$key = join($;, ($coord1, $coord2));
[download]

using $;, the "subscript separator" perl variable. The default value of which is octal 034, the control character "field separator". This isn't quite a perfect solution if your variables can store arbitrary binary data... but, in general, you're pretty safe against occurences of this character occuring in your data. You can perldoc perlvar for more details.

------------
:Wq
Not an editor command: Wq

I actually want to do thngs the other way around. I want to have the zone as the key. So that I could say, print out out all the coorsinates in zone B1. Doing this -
$coordinates{$zone} = $a1,$a2,$b1,$b2)
will only allow my to save one coordinate for a particular zone. How do I save an arbitary bumber of coordinates for each zone?

"How would I declare a hash to store this type of data?"

No, you don't declare the internal structure of the hash, whatever how complex it is, the only thing you need to declare is that it is a hash (hash ref). The actual structure is resolved on fly, as you assigning (linking) entities to the hash or any of its sub-structures.

This is not only true to Perl. Imaging that you are creating a tree in c or Java. You don't need to declare what will be linked to the tree. It could be any entity. In c, it could be void *, in Java, it could be Object. In Perl, it is a ref to something (or a scalar).

Only you care what it is, as when you retrieve it, you have to tell the computer how to cast it, whether it's a scalar, scalar ref, array ref, hash ref...