In 597 B.C. King Jehoiachin of Judah surrendered Jerusalem to the Babylonian army, and was taken into exile. (The city would later rebel and be destroyed in 586 B.C.) The Babylonians carried away 10,000 of Jerusalem's leading citizens (see 2 Kings 24:14), including the young Ezekiel, who was a priest (Ezekiel 1:2) and was soon to become a prophet.
Israel's leaders also play a dominant role in this book, because much of the blame for the sinful state of the people is placed directly on their shoulders. The foreign king who brings God's judgment upon Jerusalem is Nebuchadnezzar king of Babylon.
While the prophetic images are of Jerusalem, Ezekiel makes his prophesies from the land of Babylon.