I put 'poor' only because this old page would deserve a serious remake. Murray, as usual, as given many details not reported here. Such as:
* the diagram is wrong, king's aile of one player should face firzan's aisle of the other
* the game is only known from Muslim sources and is not attested in the Byzantium Empire. Its name of Byzantine round was given by Arabic authors who liked to say that the 'square' Shatranj was coming from East, India, and the round Shatranj was coming from West, Constantinople.
At that time Baghdad was the cultural center of the World!
This chess variant has been first mentioned by the great historian al-Mas'udî (947) and then by al-Âmulî (dead 1352). Which makes, at least, 400 years of longevity. Not so bad.