Amandus Johnson was born in Långasjö, a small village now located in the municipality of Emmaboda of Kalmar County in the historic Swedish province of Småland.
The Christianisation of the population was mainly the work of missionaries like Amandus (St. Bavo's Abbey and St. Peter's Abbey in Ghent) and Eligius (coastal region and Antwerp).
Colfe was the fourth son of Amandus, Almantius, or Aymon Colfe and his wife, Catherine Bradfield, and uncle of Abraham Colfe.