Complex sentence: In the late 6th century Pope Gregory sent a group of missionaries to Kent, to convert Æthelberht the King of Kent whose wife, Bertha of Kent, was a Frankish princess and practising Christian.
Split into simpler sentences: In the late 6th century, Pope Gregory sent a group of missionaries to Kent, to convert Æthelberht, the King of Kent. His wife, Bertha of Kent, was a Frankish princess and practising Christian.