[1][2] In early Ottoman history, the state depended on the timar system of feudal dues; but over time - especially due to the need to hire professional soldiers rather than peasants serving a feudal military obligation - more emphasis was placed on cash taxes, and avarız took over from the timar system.
[4] Initially, nüzül was seen as an alternative to avarız; nuzul was (in principle) a payment of food, in kind.
Over time, this relationship changed, and both might be demanded[5] (whilst nüzül also became a cash tax).
The name "Avarız" was also used as a blanket term for cash taxes levied by central government, or avariz-i divaniye.
Various groups were exempted from avarız on the basis of lineage, public service by favoured professions, and sometimes a district's an exceptional inability to pay (for instance, if the district had already paid heavily towards other taxes, or been ravaged by warfare).