#!/usr/bin/perl

use strict;
use warnings;

my @data = <DATA>;
chomp @data;

my @sorted =    map  { $_->[0] }
                sort { $a->[1] cmp $b->[1] }
                map  { [ $_, (split /:/)[1] ] } @data;

print "data = \n@data\n";
print "sorted = \n@sorted\n";

__DATA__
area1:place1:name1
area1:place4:name2
area3:place3:name3
area5:place2:name2

##</code><code>##

data =
area1:place1:name1 area1:place4:name2 area3:place3:name3 area5:place2:name2
sorted =
area1:place1:name1 area5:place2:name2 area3:place3:name3 area1:place4:name2