The Fursan unit, or the early Muslim cavalry unit, was the cavalry forces of Rashidun army during the Muslim conquest of Syria. The division which formed the early cavalry corps of the caliphate were commonly nicknamed the Mobile Guard (Arabic: طليعة متحركة, Tulay'a mutaharikkah or Arabic: الحرس المتحرك, al-Haras al-Mutaharikkah) or also nicknamed Marching army( جيش الزحف, "Jaish al‐Zaḥf"). These units were famously commanded by Khalid ibn Walid, the most successful early caliphate cavalry commander who organized the unit into military staff – a simple beginning of what later in military history would emerge as the general staff. Khalid had collected from all the regions in which he had fought – Arabia, Iraq, Syria and Palestine. This shock cavalry division which was led by Khalid played important roles to the victories in Battle of Chains, Battle of Walaja, Battle of Ajnadayn, Battle of Firaz, Battle of Maraj-al-Debaj, Siege of Damascus, Battle of Yarmouk, Battle of Hazir and the Battle of Iron Bridge against the Byzantine and the Sassanid. Later, the splinter of this cavalry division under Al-Qa'qa ibn Amr at-Tamimi also involved in the Battle of al-Qadisiyyah, Battle of Jalula, and the Second siege of Emesa. Later, after the Early Muslim conquests, portions of the Rashidun cavalry rebelled against central caliphate in Kharijites revolutionary movements. Historian Al-Jahiz remarked the Kharijites were feared for their cavalry charge with their lances which could break any defensive line, and almost never lost when pitted against an equal number of opponents. These Kharijites sects, believed by most scholars of Islam to have been started by Hurqus ibn Zuhayr as-Sa'di, known as Dhu Khuwaishirah at-Tamimi, Their rebellions would plague the rest of the history of the Rashidun, Umayyad, and Abbasid caliphates with endemic rebellions. This cavalry unit almost certainly rode the legendary purebred Arabian horse, by fact the quality breeding of horses were held so dearly by the early caliphates who integrated traditions of Islam with their military practice.