diff --git a/modules/simple_sitemap_sitemapindex/README.md b/modules/simple_sitemap_sitemapindex/README.md
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+# Simple XML Sitemap (SiteMapIndex)
+
+## What it do
+Extend the module: 'Simple Sitemap' for generate a [Sitemap index](https://www.sitemaps.org/protocol.html#index) to group multiple sitemap files.
+Example: https://www.euronics.it/sitemap.xml
+
+## Use
+In the backend area: `/admin/config/search/simplesitemap/variants` add a new: `variants` with a new type: `sitemapindex`
+
+Example for a website with 2 sitemap and relative index:
+```php
+pages | default_hreflang | Pages
+products | default_hreflang | Products
+sitemapindex | sitemapindex | Sitemapindex
+```
+
+To use the `Sitemap index` as the default sitemap it is necessary to set the `Default sitemap variant` with the value: `Sitemapindex` in the advanced settings:
+ `/admin/config/search/simplesitemap/settings`.
+
+After hit the button: `Rebuild queue & generate` if everything worked correctly, the value: `published` will be displayed in the Status item of the line: `Sitemapindex`
diff --git a/modules/simple_sitemap_sitemapindex/simple_sitemap_sitemapindex.info.yml b/modules/simple_sitemap_sitemapindex/simple_sitemap_sitemapindex.info.yml
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+name: 'Simple XML Sitemap (Sitemap index)'
+type: module
+description: 'Extension for the Simple XML Sitemap module for generate Sitemap index'
+configure: simple_sitemap.sitemaps
+package: SEO
+core_version_requirement: ^8 || ^9
+dependencies:
+  - simple_sitemap:simple_sitemap
diff --git a/modules/simple_sitemap_sitemapindex/simple_sitemap_sitemapindex.module b/modules/simple_sitemap_sitemapindex/simple_sitemap_sitemapindex.module
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+++ b/modules/simple_sitemap_sitemapindex/simple_sitemap_sitemapindex.module
@@ -0,0 +1 @@
+<?php
diff --git a/modules/simple_sitemap_sitemapindex/src/Plugin/simple_sitemap/SitemapGenerator/SitemapindexGenerator.php b/modules/simple_sitemap_sitemapindex/src/Plugin/simple_sitemap/SitemapGenerator/SitemapindexGenerator.php
new file mode 100644
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+++ b/modules/simple_sitemap_sitemapindex/src/Plugin/simple_sitemap/SitemapGenerator/SitemapindexGenerator.php
@@ -0,0 +1,61 @@
+<?php
+
+namespace Drupal\simple_sitemap_sitemapindex\Plugin\simple_sitemap\SitemapGenerator;
+
+use Drupal\simple_sitemap\Plugin\simple_sitemap\SitemapGenerator\SitemapGeneratorBase;
+
+/**
+ * Class VariantIndexSitemapGenerator.
+ *
+ * @package Drupal\simple_sitemap_sitemapindex\Plugin\simple_sitemap\SitemapGenerator
+ *
+ * @SitemapGenerator(
+ *   id = "sitemapindex_generator",
+ *   label = @Translation("Sitemapindex generator"),
+ *   description = @Translation("Generates a sitemapindex of your sitemaps."),
+ * )
+ */
+class SitemapindexGenerator extends SitemapGeneratorBase {
+
+  /**
+   * Generates and returns a sitemap chunk.
+   *
+   * @param array $links
+   *   All links with their multilingual versions and settings.
+   *
+   * @return string
+   *   Sitemap chunk
+   */
+  protected function getXml(array $links) {
+    $this->writer->openMemory();
+    $this->writer->setIndent(TRUE);
+    $this->writer->startSitemapDocument();
+
+    // Add the XML stylesheet to document if enabled.
+    if ($this->settings['xsl']) {
+      $this->writer->writeXsl();
+    }
+
+    $this->writer->writeGeneratedBy();
+    $this->writer->startElement('sitemapindex');
+
+    // Add attributes to document.
+    $attributes = self::$indexAttributes;
+    foreach ($attributes as $name => $value) {
+      $this->writer->writeAttribute($name, $value);
+    }
+
+    foreach ($links as $link) {
+      $this->writer->startElement('sitemap');
+      $this->writer->writeElement('loc', $link['loc']);
+      $this->writer->writeElement('lastmod', $link['lastmod']);
+      $this->writer->endElement();
+    }
+
+    $this->writer->endElement();
+    $this->writer->endDocument();
+
+    return $this->writer->outputMemory();
+  }
+
+}
diff --git a/modules/simple_sitemap_sitemapindex/src/Plugin/simple_sitemap/SitemapType/SitemapindexType.php b/modules/simple_sitemap_sitemapindex/src/Plugin/simple_sitemap/SitemapType/SitemapindexType.php
new file mode 100644
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--- /dev/null
+++ b/modules/simple_sitemap_sitemapindex/src/Plugin/simple_sitemap/SitemapType/SitemapindexType.php
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+<?php
+
+namespace Drupal\simple_sitemap_sitemapindex\Plugin\simple_sitemap\SitemapType;
+
+use Drupal\simple_sitemap\Plugin\simple_sitemap\SitemapType\SitemapTypeBase;
+
+/**
+ * Class DefaultHreflangSitemapType.
+ *
+ * @package Drupal\simple_sitemap\Plugin\simple_sitemap\SitemapType
+ *
+ * @SitemapType(
+ *   id = "sitemapindex",
+ *   label = @Translation("Sitemapindex"),
+ *   description = @Translation("The sitemap per sitemapindex type."),
+ *   sitemapGenerator = "sitemapindex_generator",
+ *   urlGenerators = {
+ *     "simple_sitemap_sitemapindex_sitemapindex_url_generator",
+ *   },
+ * )
+ */
+class SitemapindexType extends SitemapTypeBase {
+}
diff --git a/modules/simple_sitemap_sitemapindex/src/Plugin/simple_sitemap/UrlGenerator/SitemapindexUrlGenerator.php b/modules/simple_sitemap_sitemapindex/src/Plugin/simple_sitemap/UrlGenerator/SitemapindexUrlGenerator.php
new file mode 100644
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--- /dev/null
+++ b/modules/simple_sitemap_sitemapindex/src/Plugin/simple_sitemap/UrlGenerator/SitemapindexUrlGenerator.php
@@ -0,0 +1,177 @@
+<?php
+
+namespace Drupal\simple_sitemap_sitemapindex\Plugin\simple_sitemap\UrlGenerator;
+
+use Drupal\Core\Database\Connection;
+use Drupal\simple_sitemap\Plugin\simple_sitemap\UrlGenerator\EntityUrlGeneratorBase;
+use Drupal\simple_sitemap\EntityHelper;
+use Drupal\simple_sitemap\Logger;
+use Drupal\simple_sitemap\Simplesitemap;
+use Drupal\Core\Language\LanguageManagerInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\Path\PathValidator;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Class SitemapindexUrlGenerator.
+ *
+ * @package Drupal\simple_sitemap_sitemapindex\Plugin\simple_sitemap\UrlGenerator
+ *
+ * @UrlGenerator(
+ *   id = "simple_sitemap_sitemapindex_sitemapindex_url_generator",
+ *   label = @Translation("Sitemapindex URL generator"),
+ *   description = @Translation("Generates URLs for variants."),
+ * )
+ */
+class SitemapindexUrlGenerator extends EntityUrlGeneratorBase {
+
+  /**
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $db;
+
+  /**
+   * Path validator.
+   *
+   * @var \Drupal\Core\Path\PathValidator
+   */
+  protected $pathValidator;
+
+  /**
+   * SitemapindexUrlGenerator constructor.
+   *
+   * @param array $configuration
+   * @param $plugin_id
+   * @param $plugin_definition
+   * @param \Drupal\simple_sitemap\Simplesitemap $generator
+   * @param \Drupal\simple_sitemap\Logger $logger
+   * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   * @param \Drupal\simple_sitemap\EntityHelper $entityHelper
+   * @param \Drupal\Core\Path\PathValidator $path_validator
+   * @param \Drupal\Core\Database\Connection $database
+   */
+  public function __construct(
+    array $configuration,
+    $plugin_id,
+    $plugin_definition,
+    Simplesitemap $generator,
+    Logger $logger,
+    LanguageManagerInterface $language_manager,
+    EntityTypeManagerInterface $entity_type_manager,
+    EntityHelper $entityHelper,
+    PathValidator $path_validator,
+    Connection $database) {
+    parent::__construct(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $generator,
+      $logger,
+      $language_manager,
+      $entity_type_manager,
+      $entityHelper
+    );
+    $this->pathValidator = $path_validator;
+    $this->db = $database;
+  }
+
+  /**
+   * @param \Symfony\Component\DependencyInjection\ContainerInterface $container
+   * @param array $configuration
+   * @param string $plugin_id
+   * @param mixed $plugin_definition
+   *
+   * @return \Drupal\simple_sitemap\Plugin\simple_sitemap\SimplesitemapPluginBase|\Drupal\simple_sitemap\Plugin\simple_sitemap\UrlGenerator\EntityUrlGeneratorBase|\Drupal\simple_sitemap\Plugin\simple_sitemap\UrlGenerator\UrlGeneratorBase|static
+   */
+  public static function create(
+    ContainerInterface $container,
+    array $configuration,
+    $plugin_id,
+    $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('simple_sitemap.generator'),
+      $container->get('simple_sitemap.logger'),
+      $container->get('language_manager'),
+      $container->get('entity_type.manager'),
+      $container->get('simple_sitemap.entity_helper'),
+      $container->get('path.validator'),
+      $container->get('database')
+    );
+  }
+
+  /**
+   * @return array|mixed
+   * @throws \Drupal\Component\Plugin\Exception\PluginException
+   */
+  public function getDataSets() {
+    $data_set = [];
+    $sitemap_manager = $this->generator->getSitemapManager();
+    $sitemap_settings = [
+      'base_url' => $this->generator->getSetting('base_url', ''),
+      'default_variant' => $this->generator->getSetting('default_variant', NULL),
+    ];
+    $sitemap_statuses = $this->fetchSitemapInstanceStatuses();
+
+    foreach ($this->generator->getSitemapManager()->getSitemapTypes() as $type_name => $type_definition) {
+      if (!empty($variants = $sitemap_manager->getSitemapVariants($type_name, FALSE))) {
+        $sitemap_generator = $sitemap_manager
+          ->getSitemapGenerator($type_definition['sitemapGenerator'])
+          ->setSettings($sitemap_settings);
+        foreach ($variants as $variant_name => $variant_definition) {
+          // Exclude sitemapindex.
+          if (isset($sitemap_statuses[$variant_name]) && $type_name != 'sitemapindex') {
+            switch ($sitemap_statuses[$variant_name]) {
+              case 1:
+                $data_set[$variant_name]['loc'] = $sitemap_generator->setSitemapVariant($variant_name)->getSitemapUrl();
+                break;
+            }
+          }
+        }
+      }
+    }
+    return $data_set;
+  }
+
+  /**
+   * @return array
+   *   Array of sitemap statuses keyed by variant name.
+   *   Status values:
+   *   0: Instance is unpublished
+   *   1: Instance is published
+   *   2: Instance is published but is being regenerated
+   *
+   * @todo Move to SitemapGeneratorBase or DefaultSitemapGenerator so it can be overwritten by sitemap types with custom storages.
+   */
+  protected function fetchSitemapInstanceStatuses() {
+    $results = $this->db
+      ->query('SELECT type, status FROM {simple_sitemap} GROUP BY type, status')
+      ->fetchAll();
+
+    $instances = [];
+    foreach ($results as $i => $result) {
+      $instances[$result->type] = isset($instances[$result->type])
+        ? $result->status + 1
+        : (int) $result->status;
+    }
+
+    return $instances;
+  }
+
+  /**
+   * @param $data_set
+   *
+   * @return array|mixed
+   */
+  protected function processDataSet($data_set) {
+    $path_data = [
+      'loc' => $data_set['loc'],
+      'lastmod' => date('c'),
+    ];
+    return $path_data;
+  }
+
+}