Tatachwan Gangbang 〈Limited Time〉

Tatarstan is a republic in Russia, historically home to the Tatar people. There was a conflict in 1933 known as the Kazan Purge or Tatar genocide where a significant number of Tatars were executed. Maybe the user is referring to that event, but the term "gangbang" here likely is a typo for "genocide" or another term.