Question

Rumors of "sierra del plata" caused much excitement in Europe. What does "sierra del plata" mean?

Answer 1

"Silver Mountains" would be the right answer.

Answer 2

Sierra de Plata, is in fact a legend. It is said to he a mythical source of silver in South America. The myth began to spread somewhere around the 16th century. Castaways from the "Juan Diaz de Solis" expedition heard the rumor.

these are not my words but I hope it helps