Historical interpretations of John have been subject to considerable change over the years. Medieval chroniclers provided the first contemporary, or near contemporary, histories of John's reign. One group of chroniclers wrote early in John's life, or around the time of his accession, including Richard of Devizes, William of Newburgh, Roger of Hoveden and Ralph de Diceto. These historians were generally unsympathetic to John's behaviour under Richard's rule, but slightly more positive towards the very earliest years of John's reign. Reliable accounts of the middle and later parts of John's reign are more limited, with Gervase of Canterbury and Ralph of Coggeshall writing the main accounts; neither of them were positive about John's performance as king. Much of John's later, negative reputation was established by two chroniclers writing after the king's death, Roger of Wendover and Matthew Paris, the latter claiming that John attempted conversion to Islam in exchange for military aid from the Almohad ruler Muhammad al-Nasir - a story which is considered to be untrue by modern historians.

Which historians wrote early in John's life?