After the junction, the Zayul river enters India's Arunachal Pradesh where it is called Lohit.

The Zayul county borders India and Burma to the south and China's Yunnan province to the southeast.

In 1954, it was assigned to Qamdo Prefecture (昌都专区), and in 1960, it was changed to Sangngak Cho County (gsang sngag chos rdzong, 桑昂曲县).

The county seat was located in Zhowagoin Town, and it was under the jurisdiction of the prefecture-level Qamdo Region (昌都地区).

In 2020, the GDP of Zayu County is 1.144 billion yuan, and the arable land area is 41,805 mu.

The rainy season lasts from March to September, and June through August each average more than 20 days of rainfall per month.

[13] The eastern parts of the county are classified as Nujiang Langcang Gorge alpine conifer and mixed forests.

[15] Zayul County has administration over three towns and three townships:[16][17] * includes areas claimed but currently under control of the Indian state of Arunachal Pradesh.

China claims the entire Arunachal Pradesh as being part of Tibet, especially the Walong region in the Zayul River valley below Rima.