my $document = XML::LibXML->load_xml(location => 'Datei.xml');

my $xpc = XML::LibXML::XPathContext->new($document);
$xpc->registerNs(ns => $document->documentElement->getAttribute('xmlns'));
foreach my $ZN ($xpc->findnodes('//ns:Tag1/ns:Tag2'))
{
	print $ZN->findvalue('/ns:Inhalt1');
}