I love maps.
Here’s a map of who controlled things in 820 AD: States and Empires in 820
The most powerful nations at this point were the Chinese, who controlled or vassalized everything from the Caspian to the Pacific, and the Abbasid Caliphate, who in 820 invented algebra. This was the Islamic Golden Age.
By comparison, Britain was a backwater. The English language hadn’t been invented yet.