Darius and Esther (Atossa, daughter of Cyrus)

Cyrus was generally sympathetic to all local religious cults.

"Cyrus had already returned the gods carried off by Nabu-naid, not only to their native Babylonian cities, but also to Assyria and to Elam, and had rebuilt their ruined temples; it would only be following the same policy if he ordered the temple in Jerusalem to be restored, and, since the Jews now employed no images, to substitute the temple utensils for the exiled divinity."
(quoting from A.T. Olmstead, 'History of the Persian Empire', p57)

Here are a few good references related to the "Diaspora":

1) Jews in a Graeco-Roman World, ed. Martin Goodman
2) Diaspora, Jews amidst Greeks and Romans, Erich Gruen
3) The Jews in the Greek Age, Elias Bickerman

What historians/archaeologists do not recognize is that it was not the Temple of the Jews in Egypt that was ordered rebuilt, but a far less significant temple in Israel. The "home office" for Jews dispersed throughout the empire was once the capital of Egypt, Thebes (Old Jerusalem). However, starting with the Persian Period, the cult center of Karnak and Luxor in Thebes was replaced by Jebus (New Jerusalem) in Judaea/Palestine. The Jews were humbled, but then raised up again as they were still considered useful to the imperial administration.

We can now recognize that both Darius and Cyrus championed the cause of the Jews, and did so jointly. Jews recovered their status and special privileges, because they were loyalists/royalists. The royal family needed an extended network of compliant people (merchants, artisans, scribes, scouts/informants, etc.) in order to run the empire. However, for some reason, the royal family did not want the focus of Jewish worship to be directed toward Persia. Perhaps Egyptian/Amun-derived Judaism was not compatible enough with Zoroastrian beliefs (although there were certainly later Persian influences on Judaism). Darius and Cyrus certainly did not want to risk a full restoration of the Egyptian temple complex in Thebes of Egypt. Israel must have made a suitable compromise.

The Ptolemies catered to the Jews, as well, and generally received their support in return. Persian leadership was discretely replaced by Ptolemaic leadership within the Jerusalem cult. Eventually Judaism became largely homogenized based on the Torah and Jerusalem as the source and focus of their religion. Not only did the Jews thrive, but the Ptolemies along with them.

It is clear that Julius Caesar intended to continue the pre-existing "Covenant" with the Jews and the royal family (as vicars of "God").

Yet, over the succeeding generations the mostly symbiotic relationship turned deadly. It was ultimately decided to break the "Jewish network" by destroying Jerusalem, even as Thebes had earlier been destroyed because it became too "proud" and resisted the imperial will. There seems to have been a short revival of Jewish favor under Josephus/Nerva (who had proclaimed his predecessor Vespatian as "Messiah" even as the prophet Isaiah had spoked of Persian Cyrus). However, Christians were to become the new chosen "middle men" of the Kingdom.

Here are related excerpts from previous posts:

The Jewish Diaspora began as a practical element of royal administration. Leading aristocratic families were settled all over the Near and Middle East to represent the king and to pursue royal interests. Over time, these elites became a permanent fixture of local economies, but often retained many of the customs peculiar to the royal court, especially the hypochondriacal concern for ritual purity that developed over the many centuries in which disease-ridden Egypt was primary host to the royal family.

The devout Jews scattered throughout the empire were not considered a threat to Xerxes in the Persian Period, but a stabilizing influence that promoted health and welfare, especially royal welfare. They received allowance and even honor for their customs, including relief from the abject subservience expected from the less endowed. Their recently crowned champions Esther and Mordecai, now the leading Jews of the world, were attired in the royal purple.

When Judaism was officially established (or re-established) in Israel during the Persian Period, the leaders were not traditional/original/native Jews of Israel but members of the extended "Persian" ruling family. Temple life and the religion itself were firmly under Persian control. Subsequent Greek dynasties also manipulated Judaism through the appointment of High Priests and using the right of primogeniture to impose the royal bloodline of each new dynasty upon the hereditary priestly office, not only in Jerusalem but in other religious cults and locales. Each successive dynasty of kings grafted themselves onto Judaism by taking over the priesthood. Following the Persians were Greek, Maccabean, and Herodian rulers.

The Torah as a stand-alone work became something like manna falling from heaven. It was gobbled up by educated people everywhere, especially Jews of the Diaspora (Hellenized or otherwize). The interpretive keys however remained the exclusive property of the ruling elite. Nevertheless, this did not prevent various groups from developing their own interpretations, a phenomenon that continues to this day.

Gnosticism represented one major stream of naive Torah speculation. Gnostics were already predisposed to the anti-kingship sentiments of the Torah. But many of them were prepared to go even further. They were ready to denounce the very God of the Torah. Such groups were not only disenchanted with kingship as a form of government, but also with the God who supposedly ordained the perpetual tyranny.