[Salman]

But it became a rule among the Jews about 1000 years after birth of Christ.

In terms of enforcement, yes. But monogamy was always the Biblical norm, all the way back. Only one Eve in the garden.

In fact the rabbinical ruling was a response to people breaking the custom (within the letter of the law).

[A. Pole]

But monogamy was always the Biblical norm, all the way back. Only one Eve in the garden

Well, not in the Law of Moses. Many examplary persons described in the Old Testament had more than one wife and it was acceptable thing. It was the Christians who raised the moral requirement (yes, closer to the standards of Paradise) and they they were imitated by the rest of mankind.