In June 597 Columba died. At this time, Augustine landed on the Isle of Thanet and proceeded to King Æthelberht's main town of Canterbury. He had been the prior of a monastery in Rome when Pope Gregory the Great chose him in 595 to lead the Gregorian mission to Britain to Christianise the Kingdom of Kent from their native Anglo-Saxon paganism. Kent was probably chosen because Æthelberht had married a Christian princess, Bertha, daughter of Charibert I the king of Paris, who was expected to exert some influence over her husband. Æthelberht was converted to Christianity, churches were established, and wider-scale conversion to Christianity began in the kingdom. Æthelberht's law for Kent, the earliest written code in any Germanic language, instituted a complex system of fines. Kent was rich, with strong trade ties to the continent, and Æthelberht may have instituted royal control over trade. For the first time following the Anglo-Saxon invasion, coins began circulating in Kent during his reign.