By the Rio Grande
They dance no sarabande
On level banks like lawns above the glassy, lolling tide;
Nor sing they forlorn madrigals
Whose sad note stirs the sleeping gales
Till they wake among the trees and shake the boughs,
And fright the nightingales;
But they dance in the city, down the public squares,
On the marble pavers with each colour laid in shares,
At the open church doors loud with light within.
At the bell's huge tolling,
By the river music, gurgling, thin
Through the soft Brazilian air.
The Comendador and Alguacil are there
On horseback, hid with feathers, loud and shrill
Blowing orders on their trumpets like a bird's sharp bill
There is no river in Brazil named Rio Grande, so we must assume that Sitwell is referring to a large river that flows through the country.
The Rio Grande