We will learn more of Tantra next semester, but for today we will just consider Tantra within East Asian Buddhism (including some elements in Tibetan Buddhism).
In Vajrayana, there are five cosmic Buddhas, often known as Wisdom Buddhas (or Dhyani Buddhas), that each rule a different heavenly realm in the universe.
Amitabha is one of those five Buddhas (as we saw with Pure Land Buddhism).