Tax-Based to Land-Based

Chris Wickham identifies what he sees as a critical juncture in the transition away from the Roman Empire--the shift from what he calls a "tax based" to a "land based" system of finance:

Tax-raising states re much richer than most land-based ones, for property taxes are generally collected form very many more people than pay rent to a ruler from his public land. ... [T]ax-raising states have a fasr greater overall control over their territories, partly because of the constant presence of tax-assessors and collectors, partly because state dependants (both officials and soldiers) are salaried. Rulers can stop paying salaries, and have greater control over their personnel as a result. But if armies are based on landowning, they are harder to control. Generals may be disloyal unless they are given more land, which reduces the amount of land the ruler has; and, if they fire disloyal, they keep control of their land unless they are expelled y force, often a difficult task. Land-based states risk breaking up, in fact, for their outlying territories are hard to dominate in depth, and may secede altogether.

--Chris Wickham, The Inheritance of Rome (2009)

Comment: Wickham isn't quite as clear as he might be here, but I suppose his point is that the Roman Empire (and other entities of that ilk) was a free-standing self-sustaining entity with, as it were, a life of its own and an army of its own, capable of extracting wealth from just about anybody. Later "land-based" entities are essentially private deals where the superior and the subordinate agree to club together for a particular spasm of pillage (however long or short) and to split the proceeds.