Complex sentence: The historian al-Umari described its size as 20 days travel by six days travel, and its lands were more fertile and with a better climate than its Muslim neighbors; it had an army of 18,000 horsemen and "many" foot soldiers.
Split into simpler sentences: The historian al-Umari described its size as 20 days travel by six days travel, and its lands were more fertile and with a better climate than its Muslim neighbors. It had an army of 18,000 horsemen and "many" foot soldiers.