The first use of the white flag took place during the reign of the Chinese Han dynasty (25-220 CE). The flag also appeared during the Roman Empire, as mentioned by Tacitus.
The Roman scripture mentions that the Romans used the white flag as a symbol of submission in 69 CE at Bedriacum and then in 109 CE. Earlier, Roman legionaries who were surrendering, put thier shields above heads.
Why was white fabric used as a symbol of surrender? Mainly due to the fact that it was then easily available and above all easily noticeable. In addition, it was difficult to confuse her with the red banners indicating readiness to fight.