I would use glob to find the files that exist in the directory, and extract the numeric component (or 0 if there's none). Then sort those numbers in descending order, and take the first one. That gives us our highest directory.

It is then a simple matter of programming to use File::Path and create the ten new directories, adding steps of a thousand to the highest number, and prepending the stem of the directory.

In fact, minus a certain amount of fluff, it only takes two statements: one to find the highest, and one to create the directories:

use strict;
use warnings;
use File::Path 'mkpath';

my $stem = 'object';

my $highest = (
        sort {$b <=> $a}
        map { /(\d+)$/ ? $1 : 0 }
        glob("$stem*")
    )[0];

mkpath( [map {$stem . ($highest + $_*1000) } 1..10],
    1,    # verbose
    0777  # full access for everyone
);
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