What is known about the royal archives of Babylon?

Ezra 5:17 (ESV)

17 Therefore, if it seems good to the king, let search be made in the royal archives there in Babylon, to see whether a decree was issued by Cyrus the king for the rebuilding of this house of God in Jerusalem. And let the king send us his pleasure in this matter.”

During the reign of Darius, Babylon was the capital of the satrapy of Trans-Euphrates and would thus be the repository of all records concerning its provinces. Many of these documents would have been clay tablets or cylinders although some might have been papyrus or leather scrolls.1 In contrast to the people mentioned in Ezra 4:7–22, Tattenai appears to be quite neutral. He asks for the archives to be searched to determine if the Jews are speaking truthfully. If there is one place you would expect to find Cyrus’ decree, it will be in Babylon. This is where the royal archives were kept, it is where Cyrus was when he issued his decree and it is the place from which the Jews came back to Jerusalem.