[5] The semi-tropical forests found at elevations above 2,000 metres (6,600 ft) in the upper parts of the Zaña basin are an unusual feature of the river.

The existence of the forests is due to the relatively low elevations of the Andes in this region between the desert coasts of western Peru and the rainforests of the Amazon Basin of the east.

The Peruvian government recognized the uniqueness of the forests in 2010 by creating the "Reserved Zone of Udima" consisting of 30,503 hectares (75,370 acres) of land overlooking the headwaters of the Zaña.

The canals built by the people of Nanchoc at that time were utilized to irrigate crops such as peanuts, squash, manioc, and chenopods, a relative of Quinoa.

[8] In 2019, Peruvian archaeologist Walter Alva discovered the ruins of a megalithic temple in the Zaña Valley near Oyotun.