In 738, Quiriguá, a vassal of Copán, Tikal's key ally in the south, switched allegiance to Calakmul, defeated Copán and gained its own independence. It appears that this was a conscious effort on the part of Calakmul to bring about the collapse of Tikal's southern allies.Looper 2003, p.79. This upset the balance of power in the southern Maya area and lead to a steady decline in the fortunes of Copán.Wyllys Andrews & Fash 2005, p.408.
In 738 Quiriguá a vassal of Copán Tikal's key ally in the south switched allegiance to Calakmul defeated Copán and gained its own independence It appears that this was a conscious effort on the part of Calakmul to bring about the collapse of Tikal's southern alliesLooper 2003 p79 This upset the balance of power in the southern Maya area and lead to a steady decline in the fortunes of CopánWyllys Andrews & Fash 2005 p408