Steam Power... 1000 Years Early

In this scenario play as almost anything you want, within the confines of the normal possible things in the 8th century, plus anything steam related. Build a trail into the wild west, or study combustion in China. With only one catch. No extra tech (unless you invent it) and there's also an evil megalomaniac warlord. Find out what would happen if steam was introduced 10 centuries sooner.