Complex sentence: We know almost nothing about the life of "Manchán of Mohill", except that he founded the early Christian monastery of Mohill, in county Leitrim, in either the early 6th or 7th century.
Split into simpler sentences: We know almost nothing about the life of "Manchán of Mohill". He founded the early Christian monastery of Mohill, in county Leitrim, in either the early 6th or 7th century.