The Sultanate of Ifat, led by the Walashma dynasty with its capital at Zeila, ruled over parts of what is now eastern Ethiopia, Djibouti, and northern Somalia. The historian al-Umari records that Ifat was situated near the Red Sea coast, and states its size as 15 days travel by 20 days travel. Its army numbered <answer>15,000</answer> horsemen and 20,000 foot soldiers. Al-Umari also credits Ifat with seven "mother cities": Belqulzar, Kuljura, Shimi, Shewa, Adal, Jamme and Laboo.
According to al-Umari, how many cavalry did the Sultanate of Ifat have?
15,000