(or Bii-Khem), a river in the Tuva ASSR; the right tributary of the Enisei River. It is 605 km long and has a basin of 56,800 sq km. It takes its source from Lake Kara-Balyk and flows mainly through the mountains of the northeastern part of Tuva. Its chief tributaries from right to left are the Azas, Khamsara, and Systyg-Khem. Near the city of Kyzyl, the Bol’shoi Enisei merges with the Malyi Enisei (or Ka-Khem) River to form the Verkhnii Enisei (or Ulug-Khem).