 During the reign of Nebuchadnezzar. But here it is, 605 B.C., he takes these guys and he's going to indoctrinate them in the literature and language of the Chaldeans. Chaldeans is just a synonym for Babylonians. They were known as Chaldeans before they were Babylonians. Remember, Abraham came from Babylon. He came from Ur of the Chaldeans.