Position of Tschuna in the west of the catchment area of the Angara
The Tschuna (Russian Чуна, scientific transliteration Cuna, also Chuna or Cuna and called in the upper reaches Uda ) is the right or southeastern source river of Tassejewa in Siberia, Russia ( Asia).
The river rises in the southwest of Irkutsk Oblast as Uda in the center of the Ostsajans, whose mountains to 2924 m high in the headwaters of the Tschuna. It flows thence in a northerly direction into the central Siberian Plateau one that is up to 530 m high along the river now called Tschuna. Therein it flows under different about Nischneudinsk and Lessogorsk after Balturino. Then the Tschuna used - approximately parallel to the a little further west running Birjussa fluently - gradually to the northwest until it forms approximately 250 river miles below Tschunojar with the Birjussa the Tassejewa.
In Balturino the Tschuna is crossed from west to east direction from a bridge of the Baikal - Amur Mainline.