The king’s letter gives two interesting clues as to why he was motivated to grant Ezra so many resources and so much authority. In Ezra 7:14 he gives Ezra the task of making inquiries about what is happening in the province of Yehud, and in Ezra 7:23 he says, Why should there be wrath against the realm of the king and of his sons?
From this it appears that his primary motivation was to appease the people of Jerusalem and prevent trouble in his realm.
In 460 BC the Egyptians had revolted against his rule and in 459 BC Persian forces had crushed the rebellion with the help of the Athenians. Given the fact that this rebellion had taken place, the king was most certainly eager to prevent another revolt in another part of his empire. The Persians wanted to encourage moral and religious authority among their subjects in order to enhance public order.1 The large gifts provided for the temple would thus have encouraged the Jews to look with favour on Artaxerxes and to pray for him.2
11 This is a copy of the letter that King Artaxerxes gave to Ezra the priest, the scribe, a man learned in matters of the commandments of the LORD and his statutes for Israel: