A commodity supply chain is a sequence of handovers: production, aggregation, transport, storage, processing and final delivery. Each handover introduces cost, time and a point at which information can be lost.
Concentration matters. Where a single port, terminal or route carries a disproportionate share of a flow, disruption at that point propagates widely and quickly.
Storage and inventory act as shock absorbers. When inventories are thin, small disruptions produce large price responses; when they are ample, the same disruption may pass largely unnoticed.
For businesses buying internationally, mapping their own chain — including the parts controlled by suppliers — is often the single most useful exercise available to them.