From the time of Procopius in the reign of Justinian, the equestrian imperial statue on the Column of Justinian in the Augustaion beside Hagia Sophia, which gestured towards Asia with right hand, was understood to represent the emperor holding back the threat to the Romans from the Sasanian Empire in the Roman–Persian Wars, while the orb or "globus cruciger" held in the statue's left was an expression of the global power of the Roman emperor. Subsequently, in the Arab–Byzantine wars, the threat held back by the statue became the Umayyad Caliphate, and later, the statue was thought to be fending off the advance of the Turks. The identity of the emperor was often confused with that of other famous saint-emperors like Theodosius the Great and Heraclius. The orb was frequently referred to as an apple in foreigners' accounts of the city, and it was interpreted in Greek folklore as a symbol of the Turks' mythological homeland in Central Asia, the "Lone Apple Tree". The orb fell to the ground in 1316 and was replaced by 1325, but while it was still in place around 1412, by the time Johann Schiltberger saw the statue in 1427, the "empire-apple" () had fallen to the earth. An attempt to raise it again in 1435 failed, and this amplified the prophecies of the city's fall. For the Turks, the "red apple" () came to symbolize Constantinople itself and subsequently the military supremacy of the Islamic caliphate over the Christian empire. In Niccolò Barbaro's account of the fall of the city in 1453, the Justinianic monument was interpreted in the last days of the siege as representing the city's founder Constantine the Great, indicating "this is the way my conqueror will come".