Theme Widget Area Defaults

Question

In my custom theme's function.php file, I have created a widget area:

function my_footer_widget_area() {
    $args = array(
        'id' => 'footer_widget_area',
        'class' => 'my_widget_footer',
        'name' => __('Footer Widget Area', 'mynamespace'),
        'description' => __('Widgets for the footer. The widget title will appear above the widget content. Leave the title blank to only display widget content.', 'mynamespace'),
    );
    register_sidebar($args);
}

Which is activated with

add_action('widgets_init', 'my_footer_widget_area');

The theme's sidebar.php file contains

if (is_active_sidebar('footer_widget_area')): ?>
    <div id="tertiary" class="footer-container" role="complementary">
        <div class="footer-inner">
            <div class="widget-area">
                <?php dynamic_sidebar('footer_widget_area');?>
            </div><!-- .widget-area -->
        </div><!-- .footer-inner -->
    </div><!-- #tertiary -->
        <?php else: ?>
        <!-- Time to add some widgets! -->
    <div id="tertiary" class="footer-container" role="complementary">
        <div class="footer-inner">
            <div class="widget-area">
  <!--  <p>footer sidebar  - not active</p>    -->
            </div>
        </div>
    </div>
<?php endif;

When the theme is activated, the widget area is active, but the widget area contains widgets.

How do I create the widget area with no widgets in that widget area? Are there default widgets assigned to a created widget area? If so, how do I disable those default widgets?