The medieval knight Sir Arthur started his journey in medieval Europe where Christianity was the main religion and Justinian ruled from 527-565 C.E
The Byzantine Empire was similar compared to the Roman Empire and had chariot racing as well as celebrated imperial birthdays and both practiced Christianity. But the Byzantine Empire's capital was Constantinople and followed Roman Law, Justinian's Code and Ecolga while under the governance of Justinian in a Feudal system.
The beginnings of Islam originated in the Arabian Peninsula and eventually led to the rise of Islamic empires. Islam is practiced by muslims who worship god and believe that Muhammad is god's messenger. The Arab Muslims expanded to the Byzantine and Sassanian empires that were weak after a period of fighting with one another and also from disease, environmental problems and the Turks. This gave the Arab Muslims an advantage to conquer.
There once was a knight named Sir Arthur who was known to be the strongest and bravest knight on the fief.