If you allow Perl to tell you about things it considers weird, you'll get more information:

use warnings;

my $text="ABCDE<\/Text>TUVWX";

my @splitted=[];

@splitted=split("\<\/Text\>".$text);

print "0.".$splitted[0]."\n";
print "1.".$splitted[1]."\n";
__END__
Use of uninitialized value $_ in split at tmp.pl line 7.
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This is because you only pass one argument to split, instead of two arguments.

One argument is because of the dot instead where you would want to write a comma:

@splitted=split("\<\/Text\>".$text);
#                           ^
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Also, the first argument to split is a regular expression, not a string. You might want to change your code to accomodate that:

@splitted=split(m!\<\/Text\>!, $text);
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