Upper tunguska

What is Upper tunguska?

Upper tunguska definition and meaning on Dictionary terms:
noun

any of three tributaries of the Yenisei River in the central Russian Federation in Asia: the Lower Tunguska, 2000 miles (3220 km) long; the Upper Tunguska or the lower course of the Angara, 1151 miles (1855 km) long; and the Stony Tunguska, about 975 miles (1570 km) long.