The Dzong is built on a ridge, at the base of which flows the Dongdi Chu. It is accessibly by road and is four kilometers away from the main town of Chorten Kora.

Dongdi Dzong is one of the oldest Dzongs in Bhutan. Its history dates to the 19th century. Gongkhar Gyal, grandson of Lhasey Tshangma, who had established himself in Tshenkharla, was invited by the people of the region in Trashiyangtse, known as Donglum, to their leader. He accepted the offer and, choosing a strategic location, built a small khar (castle). The khar was named Dongdi Dzong, as its base was the Dongdi Chu. At a later unknown date it was attacked by the Tibetans. The people of Donglum region fled and the Dzong fell into ruins.

In the 15th century Terton Pema Lingpa, on his visit to Trashiyangtse, came across the ruins of the old castle. He rebuilt the Dzong and renamed it Trashiyangtse Dzong, the fortress of auspicious fortune. In the 17th century, when the Trongsa Penlop Chogyal Minjur Tempa launched an eastern military campaign to bring the six eastern regions under Drukpa rule, the ruler of Trashiyangtse, King Jigdra, submitted to the Penlop’s forces without a challenge. In 1648 Minjur Tempa further renovated as well as extended the Dzong.

The Dzong was used as an office by the Dungpas (sub district administrator) till 1992. As Trashiyangtse became a separate Dzongkhag, a new Dzong farther up the valley was built, and the old Dzong was used by the Dzongkhag Monastic Body. The Dzong also played an important role in maintaining the security of the country, since Trashiyangtse borders on Chinese Tibet in the north and the Indian State of Arunachal Pradesh in the East.

The Ta Dzong and the Chu Dzong (water storage fort) are in ruins. The utse is a three-storied structure renovated in 1975 at the initiative of the Royal government of Bhutan. The utse has a statue of Chuchizhey (Avaloketeshvara) as its main relic. Additional important relics are a statue of Zhabdrung Ngawang Namgyal, Guru Padam Sambhava, Lord Buddha, Guru Nima Wozer, Chenrizi, 100 volumes of Kanjur, and another 108 volumes of small prints. The Dzong also has a treasure phurpa (ritual dagger) discovered by Pema Ling. The utse also has a Gonkhang which houses the Mahakala, Mahakali and the Raven.