Listeros,

Shifts in trade patterns contributed to the Maya collapse. The key
trade item was obsidian for making tools and weapons. Obsidian trade
flowed along inland riverine networks early on. But in time, it was
traded by way of coastal trade networks. Inland centers began to
decline as coastal centers flourished. The shift in trade involved
inland centers also being cut off from other goods. The Field Museum
researchers studied sites in Mexico, Honduras and Guatemala for
obsidian trade details. The trade was analyzed from 250-1520 CE.
Perhaps riverine trade had become dangerous and the development of
larger canoes may have made seagoing transport more efficient.
The study will be published in the journal Antiquity.

EurekAlert has the story here;
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