Complex sentence: Later tradition states that between the years 665 and 667 St. Colman founded several churches in Scotland before returning to Iona, but there are no seventh-century records of such activity by him.
Split into simpler sentences: Later tradition states that between the years 665 AD and 667 AD, St. Colman founded several churches in Scotland before returning to Iona. However, there are no seventh-century records of such activity by him.