Song and Gallimard are talking about China and how it is viewed in today's world. Song reflects sadly that although China used to rule the world in the past, that counts for nothing in today's world, where they seem to be relatively powerless compared to the European nations such as France, where Gallimard comes from. This is when Song dreams of how exciting it would be to rule the world in today's times rather than merely in the past:
We Chinese--once, I suppose it is true, we ruled the world. But so what? How much more exciting to be part of the society ruling the world today.
This of course foreshadows the rise in power that China experiences and continues to experience in today's world. Song's comment reflects the way in which China has gradually and significantly grown in the amount of world power it has because of its status as one of the leading countries in terms of the economy, workforce and power that it therefore has. Although ironically Song bemoans the lack of power that China has, this comment actually seems to foreshadow the future power and prestige that China enjoys today.