OK, I'll bite. What does "635 C.E." mean? What happened to "BC" and "AD"?
The find was made in Israel.
It’s a courtesy to non-Jewish readers who use the pagan Gregorian calendar that has become common since the Roman Empire imposed it.
The actual year would be AM 4395, but a typical common reader of such an article doesn’t understand the Hebrew Calendar.
So the “common” date is used.