I am a Dutch author and I am writing a book about Ancient Egypt with lots of dates. My question is: can I use for instance 4,510 B.C.E. instead of 4510 B.C.E. Is there a rule for using the comma in dates?
Generally, we don't include commas in years. The current year is 2015, not 2,015.
However, if the year contains five or more digits, then you generally do add a comma. So there is no comma in 4510 B.C.E., but if you went even further into the past, you would add a comma to 14,510 B.C.E.
I found a few style guides to back this up, such as this one from National Geographic, and this one from ESC. Style guides offer suggestions, rather than hard-and-fast rules, and different organizations may have different suggestions. However, I think this suggestion is pretty consistent. We definitely write modern years, such as 1996, without commas, so it makes sense to write older years in the same way. Adding commas to larger numbers makes them easier to read, so you should do this with years, as well (10000000 B.C.E. is hard to understand at a glance, you have to pause in your reading for a second to count the zeroes; 10,000,000 B.C.E. is much easier to read).