“the king of Assyria.” The king of Persia was the “king of Assyria” at the time of Ezra by virtue of the huge size of the Persian empire, but that is not likely why the king of Persia is called “the king of Assyria” in this verse, which, on the surface seems anachronistic since Assyria fell to the Babylonians in 612 BC. The expression is likely to contrast the kings of Assyria, who were hostile to Israel and Judah, with this king of Persia who was now ruler over the territory of Assyria and yet supportive of Israel. We must also remember that the people of the nation of Israel, the ten northern tribes who had been carried away to Assyria, were forcibly taken to Assyria, and perhaps some of them took advantage of this opportunity to return to Israel and Judah, and the text is subtlely making that point.