Cissa was reported as the viceroy of king Centwine of Wessex (reigned c. 676–686). Cissa is sometimes said to have himself been a king of Wessex, but does not feature in the king lists or genealogies. He is said to have constructed Chisbury Camp, and to have founded Abingdon Abbey.

• Kelly, S. E. 2000. Charters of Abingdon Abbey, part 1. Anglo-Saxon Charters 7.

• Cissa 1 at Prosopography of Anglo-Saxon England