Recommend a 'Domain-game' fantasy novel not on the ACKS reading List

The Sagas of the Icelanders, while more historical-with-embellishments than pure fiction, definitely covers the high-level ground. Adventurers become landholders, gather groups of hundreds of warriors, deal with invasions and untrustworthy kings and tax collection, etc. Just started reading them, interesting stuff.

Ditto the Sagas
and
Samurai William by Giles Milton
This being the historical account of the englishman who rose to power in 16th century Japan and which inspired the fictional story:
Shogun, by James Clavell