diff --git a/lang/en/moodle.php b/lang/en/moodle.php
index 55e19c4fc30..e465469e338 100644
--- a/lang/en/moodle.php
+++ b/lang/en/moodle.php
@@ -222,6 +222,8 @@ $string['block'] = 'Block';
 $string['blockconfiga'] = 'Configuring a {$a} block';
 $string['blockconfigbad'] = 'This block has not been implemented correctly and thus cannot provide a configuration interface.';
 $string['blocks'] = 'Blocks';
+$string['blocks_main'] = 'Main content blocks';
+$string['blocks_supplementary'] = 'Supplementary blocks';
 $string['blocksaddedit'] = 'Add/Edit blocks';
 $string['blockseditoff'] = 'Blocks editing off';
 $string['blocksediton'] = 'Blocks editing on';
diff --git a/lib/classes/output/core_renderer.php b/lib/classes/output/core_renderer.php
index 592a1f72476..99a156e0f2c 100644
--- a/lib/classes/output/core_renderer.php
+++ b/lib/classes/output/core_renderer.php
@@ -3817,6 +3817,7 @@ EOD;
      */
     public function blocks($region, $classes = [], $tag = 'aside', $fakeblocksonly = false) {
         $displayregion = $this->page->apply_theme_region_manipulations($region);
+        $headingid = $displayregion . '-block-region-heading';
         $classes = (array)$classes;
         $classes[] = 'block-region';
         $attributes = [
@@ -3824,12 +3825,23 @@ EOD;
             'class' => join(' ', $classes),
             'data-blockregion' => $displayregion,
             'data-droptarget' => '1',
+            'aria-labelledby' => $headingid,
         ];
+        // Generate an appropriate heading to uniquely identify the block region.
+        $blocksheading = match ($displayregion) {
+            'side-post' => get_string('blocks_supplementary'),
+            'content' => get_string('blocks_main'),
+            default => get_string('blocks'),
+        };
+        $content = html_writer::tag('h2', $blocksheading, ['class' => 'visually-hidden', 'id' => $headingid]);
         if ($this->page->blocks->region_has_content($displayregion, $this)) {
-            $content = html_writer::tag('h2', get_string('blocks'), ['class' => 'visually-hidden']) .
-                $this->blocks_for_region($displayregion, $fakeblocksonly);
-        } else {
-            $content = html_writer::tag('h2', get_string('blocks'), ['class' => 'visually-hidden']);
+            $content .= $this->blocks_for_region($displayregion, $fakeblocksonly);
+        }
+        // Given that <aside> has a default role of a complementary landmark and is supposed to be a top-level landmark,
+        // blocks rendered as part of the main content should not have a complementary role and should be rendered in a more generic
+        // container.
+        if ($displayregion === 'content' && $tag === 'aside') {
+            $tag = 'section';
         }
         return html_writer::tag($tag, $content, $attributes);
     }