The Spanish Silver Train was a mule trail used by colonial Spain to transport Peruvian silver across the Isthmus of Panama. Its purpose was to link the shipping along the Pacific coast of South America with the trade routes in the Caribbean Sea and Atlantic Ocean, allowing goods from the Spanish colonies in the south to reach mainland Spain in Europe.

Early on in Spain’s colonization of the Americas, the conquistador Francisco Pizarro conquered the Incan Empire, which was based in Peru. Spaniards also expanded their kingdom’s holdings over Chile, to the south. These regions contained vast quantities of wealth, primarily in the Peruvian silver mines, which Spain mostly wanted to ship east across the Atlantic, to enrich mainland Spain and to fund wars in Europe.

To accomplish this, Spanish ships would carry silver northward along the Pacific coast of Peru to the Isthmus of Panama, which was narrow enough to allow the treasure to be easily transported overland to the Caribbean. The silver train was the overland portion of this journey. Mule trains would pick up the shipments landing from Peru, carry it along the trail across Panama, and drop it off in the city of Nombre de Dios. It remained there until the annual Spanish treasure fleet arrived, which picked it up and make the long Atlantic voyage back to Spain proper.

Because the silver train carried such enormous wealth, while remaining slow and predictable (unlike ships), it ran the risk of being attacked. Indeed, in 1573, the English privateer Francis Drake carried out a land-based raid on the mule trains following his 1572 capture of Nombre de Dios, netting him and his crew large amounts of treasure. After these attacks, Nombre de Dios fell out of favor as the endpoint trail’s endpoint, and the silver was instead sent to the safer city of Portobelo.