The battle of khandaq is so called because the Muslims dug a ditch to protect and defend the city. The word khandaq (ÎäÏÞ) is the Arabised form of the Middle Persian word kandag (˜äÏ; meaning "that which has been dug"). Salman the Persian advised Muhammad to dig a trench around the city. The battle is also referred to as the Battle of Confederates.