River which has its source in the Fountains Valley and flows through Pretoria. Said to have been named after the large population of Vervet monkeys that lived in trees on its banks, between Daspoort and the Fountains Valley. An alternative theory for its name, is that it's taken from Tshwane and means 'little monkey or monkey-coloured'.
References
New Dictionary of South African Place Names by Peter E. Raper
Further Reading
https://www.tripadvisor.co.za/Tourism-g312583-Pretoria_Gauteng-Vacations.html