What is 69?

It's a pretty calm evening, well, in my world. I'm pretty good at ignoring the screaming girls running around. A friend is over which only seems to amplify things. But I'm in my happy zone. I'm in the kitchen baking cupcakes and a single cake for a baby shower. I scored on some things at Orson Gygi today, and I'm mulling over in my mind how to tackle the current cake project, while taking note of two more that are coming up next week. After a day of number crunching, my creativity gets to start flowing. Brynn is sitting on a bar stool on the other side of the counter, watching me.
"Mom, what does 69 meant?"
I pause. In a flash second I take note of the rule I promised myself I would always follow. If they're old enough to ask, they're old enough to know. But I also like to stick with the rule to keep the information age appropriate. I don't know enough about where she's coming from with this to know how I should proceed so I ask, "what do you mean? Where did you hear it?"
"When we read that Cleopatra was born in 69."
A flood of relief that I had decided to ask a little more. Can you imagine had I just plunged in with an answer on "69"???? Brynn has just done a book report on Cleopatra and we found out that she was born in 69 B.C.
I think I'd much rather explain B.C. and A.D. to my child than... well, I'm actually going to be OK if I never have to explain the alternative with her.