Complex sentence: The modern calendar, as well as regulating the immediate year, is part of a system of chronology that allows events to be dated far into the future and the past so a given date includes day, month and year.
Split into simpler sentences: The modern calendar, as well as regulating the immediate year, is part of a system of chronology that allows events to be dated far into the future and the past. So a given date includes day, month and year.