1) Song Dynasty of China - 960-1279 CE
Equivalent rulers of the Middle East and Africa during this period: Islamic Caliphates and the Turkish Empire (pre-Ottoman Empire)

2) The biggest difference is the access to oceans and large rivers. Without the rivers, the Andean cultures also lacked the fertile floodplains that these other three locations had.

3) A capital on the important trade routes between Europe and Asia led to the strengthening of the Byzantine economy, and various social and military revisions allowed the Empire to regain some of its strength. It lacked several of the outside invaders that the Western Roman Empire dealt with, and with the strengthening economy and social reforms it avoided the political corruption and trade difficulties that crippled the Western Romans.

4) The Mongols.

5) Samurai were the Japanese equivalent to European Knights. Each held a bit of land, were held to a particular code of conduct, and paid respects and fealty to a local lord.