The Subansiri[a] (Chayul Chu in Tibet)[1] is a trans-Himalayan river and a tributary of the Brahmaputra River that flows through Tibet's Lhuntse County in the Shannan Prefecture in Southwestern China, and the Indian states of Arunachal Pradesh and Assam.

[4] In early maps of independent India, Tsari Chu was marked as the main Subansiri river.

Obonori reflects the community's deep connection with the river, which is central to their culture, economy, and spiritual life.

The exact etymology of Obonori is tied to the Mising people's unique linguistic and cultural heritage.

Its valley, called Nyelto, includes important towns such as Ritang and Kyitang, the latter the capital of Lhuntse County.

Chayul Chu flows for about 50 km in Tibet before entering Arunachal Pradesh near the town of Taksing.

[3] Tsari Chu (Chinese: 洛河; pinyin: Luò hé, "Lo River"; known as Lensi River in Arunachal Pradesh)[7] rises near the village of Chosam in Tibet and flows east for about 25 miles till the town of Migyitun, where it turns south.

[10] The holiness comes from the Dakpa Sheri mountain peak at the centre of the Tsari district, considered the home of the Buddhist Tantric deity Demchok (Chakrasamvara) and his consort Dorje Phagmo (Vajravārāhī).