Economy (Exalted)

Noone can manage more than Resources 5 alone, and that's a full-time job. Half of all people live in the Realm = 50 000 000 90% are farmers, with an average family size of 5, and 1/2 obol income per farmer family. This means an average income of 4 500 000 obols per year. The mountain tax should probably be about 10 000 000 obols a year, or about 1024 talents. 500 cities and autocracies pay taxes to the Realm, with only 4/10 getting through. Say 20 000 live in each city. That means an average income of 500*20000/2= 5 000 000. That's 2 000 000 getting through, with 3 000 000 disappearing along the way, mostly to the pockets of the Great Houses. That's a total of about 15000 talents per year or about the equivalent of Resources 7 per year. Now we haven't counted the income tax, but it probably bumps the Resources to 8.

Nexus
If Nexus has a population of 1 000 000, they should have 5 Resources 5 based on pure farming population. Let's say merchants produce income tax equal to 10 times that: 5 Resources 6. Say a clean 7, when calculating everything. That's a lot.