Why is Peruvian Brown so named?
Solution 1:
The colour seems to be similar to that of traditional Peruvian clay pots, and also to the colour of Peruvian leather. I cannot verify either of these theories, sorry.
Solution 2:
My guess is it's from Gossypium barbadense, a species of cotton plant grown in Peru. From 1880, Peruvian Bark: A Popular Account of the Introduction of Chinchona Cultivation Into British India
In a crop of G. Barbadense a percentage of the plants almost always yields cotton of a reddish-brown colour.