The crescent and star, while generally regarded as Islamic symbols today, have long been used in Asia Minor and by the ancient Turks, earlier than the advent of Islam. According to one theory, the figure of the crescent has its roots in tamghas, i.e. markings used as livestock brand or stamp, used by nomadic Turkic clans of Central Asia. One of the most popular legends regarding the Flag of Turkey is that, in a pool of blood of Turkish warriors, there was a reflection of the crescent moon and a star. Three theories have been put forward regarding the possible location and context of this event, which include: In a dream of Osman I, the first Ottoman Sultan, a crescent and star appeared from his chest and expanded, presaging the dynasty's seizure of Constantinople. A crescent and star were spotted on the night of the fall of Constantinople to Mehmed II in 1453.