Theoretically, the Caliphate includes all the areas claimed by Believers (Followers of Ela), with the Caliph as the leader of the Faith. In practice, the Caliph only controls what we would consider the Middle East and Northern Africa.
The Caliph maintains a large army (one of his titles is Protector of the Faithful), mostly to fend off attacks from Chulan Toz, the expansionist hobgoblin kingdom on his eastern border, and to keep barbarians from the steppes from overrunning the Caliphate. The Caliph has a fragile truce with his traditional rival, the Skandrian Empire. He also maintains a navy, and the Caliphate is a major sea force. Its merchant ships range all over the world.
Much of the cultural information for Krosa also holds true for the Caliphate.