Hmmm, Singapore is another example of a "middle", although rather far in the direction of "dictatorship". Not sure if we've seen much of it before the 20th Century, then again they're a modern form of oligarchy.

It's definitely not the best exponent of what I was trying to get across, but I didn't say all that much initially. At least when they're not fighting wars, or are degenerate cases like the Saudi royal "family" (15,000 members, 2,000 with wealth and power per Wikipedia), there tend to be limits to their rapaciousness. Much less so with traditional oligarchies.