<?php if(get_the_archive_description()) {?>
					<?php	the_archive_description( );	?>
					<?php }   ?>

					<?php if(!get_the_archive_description()) {?>
					<?php if ( ! dynamic_sidebar( 'sidebar-4' ) ) : ?>
					<aside id="search" class="widget widget_search"><?php get_search_form(); ?></aside>
					<?php endif; // end sidebar widget area ?>	

					<?php }?> <!-- ends the second outer condition -->

The second condition is a widget region