Complex sentence: There is no agreement on the name or exact range of birth dates with some sources starting them at the mid or late 1990s or the more widely used period from the mid 2000s to the present day.
Split into simpler sentences: There is no agreement on the name or exact range of birth dates. Some sources start it at the mid or late 1990s or the more widely used period from the mid 2000s to the present day.