I have also thought about the Song Dynasty sometimes, but never used it for anything. I even like the art from that period. It's generally more elegant than the "baroque" T'ang dynasty. If I remember correctly, they used gas fires in some areas, for heating and cooking and such, maybe some smelting processes.

The empire was under constant pressure from outside, which lead to an inflated army. Their borders might have had a bit of an insecure "frontier" feeling sometimes. There were some secret societies, which had a long history in China, often with some elements of mafia, rebellion, and religion all mixed together. China had a long history of extreme contrast between rich and poor which may have been one of the draws of these secret societies  (and sadly much later made the Communist part attractive).