There is a limitation for date controls. You cannot enter years earlier than 1400-ish, and for years prior to 1901 you cannot enter exact dates.

I recommend using Biography field for storing ancient dates if you really have to have it logged somewhere.

I will look into fixing it some time, but there are certain technical problems with it which needs to be solved before I can fix this issue.

I am sorry for the inconvenience.

Andrei