The Migrate API started as a contrib module in Drupal 6 and 7. From the start, it was designed to handle large-scale projects, creating Drupal nodes, taxonomy terms, etc., from almost any source: another Drupal site, an XML or CSV file, or the database from another CMS. The base module kept track of what had already been brought into the site, so it supported incremental migrations as well as updates of previously migrated content.
In order to use these versions of the Migrate API, the site