Arianism is the doctrine established by Arius. It is important to mention that our primary sources on the Arian crisis are very poor. Most of our knowledge comes from his opponents, that is, Athanasius of Alexandria and others. The Arians played an important role in Church history until their extinction around 395 a.d.
Arianism spread throughout the West and most of the Germanic tribes and barbarians who adopted the Christian faith were Arian. Until the sixth century, many kingdoms in the West were Arian, such as the Goths and the Visigoths. The Arians possessed a church in Constantinople itself. Byzantine emperors turned a blind eye to their existence because they depended on them as soldiers in the army. Ironically enough, in the East where it started, and mainly in Alexandria, the Arians lost their defenders soon after Arius’ death.