The Kosi or Koshi (, , , ) is a trans-boundary river which flows through Tibet, Nepal and India. It drains the northern slopes of the Himalayas in Tibet and the southern slopes in Nepal. From a major confluence of tributaries north of the Chatra Gorge onwards, the Kosi River is also known as Saptakoshi (, ) for its seven upper tributaries. These include the Tamor River originating from the Kanchenjunga area in the east and Arun River and Sun Kosi from Tibet. The Sun Koshi's tributaries from east to west are Dudh Koshi, Bhote Koshi, Tamakoshi River, Likhu Khola and Indravati. The Saptakoshi crosses into northern Bihar, India where it branches into distributaries before joining the Ganges near Kursela in Katihar district.