The Muslims' light cavalry during the later years of the Islamic conquest of Levant became the most powerful section of the army. The best use of this lightly armed and fast moving cavalry was revealed at the Battle of Yarmouk (636 A.D) in which Khalid ibn Walid, knowing the importance and ability of his cavalry, used them to turn the tables at every critical instance of the battle with their ability to engage and disengage and turn back and attack again from the flank or rear. A strong cavalry regiment was formed by Khalid ibn Walid which included the veterans of the campaign in Iraq and Syria. Early Muslim historians have given it the name Tulai'a Mutaharrika (طليعة متحركة), or the "mobile guard". This was used as an advance guard and a strong striking force to route the opposing armies with its greater mobility that gave it an upper hand when maneuvering against any Byzantine army. With this mobile striking force, the conquest of Syria was made easy.