The older dates didn't seem to be working properly in WorldCat Identities, so I've been looking at records in WorldCat with early dates. In our March 2007 copy of WorldCat there are 828 records with BCE dates. Since there are only 7,500 records with a date of 1450 or earlier, it can be difficult to find Identities records with early dates, especially since many of the very early materials described are things like mummy cloths or coins or tablets without a clear name associated with them for Identities.
For sharing, I made a WorldCat list of the ten oldest items I found. Here is an edited version:
We'll have those BCE dates in Identities working properly soon.