The development of a monetary system in a specific unit of account is one mode of directing resources towards the centre - to mark contributions from people before they are due and give out uniform receipts, tokens, in return.
Historically, system design may blend, with challenges, the ideologies of nominalism and metallism. Money in this context was always a compound of value with a count. Arbitrage opportunities destabilised money supply patterns, principally, when nominal face value diverged from bullion content. Although never simply metallism, bullion content mattered greatly. Supply shortages bedevilled both medieval and later commodity monetary systems.
Money is a unit of account. Its payments and collections; an ongoing politically engineered market-based project.