In the old days (1000-1471), Binh Dinh was an imperial city of the Kingdom of Champa. Scores of historical events took place here during five centuries. The kingdom left many vestiges, including some citadels: Vijaya, Cha, and Thi Nai.
Thi Nai citadel was located in an area belonging to hamlets of Binh Lam, Binh Nga Dong, Binh Nga Tay, and Binh Trung in Tuy Phuoc district. It was closely related to important events taking place in the history of the Kingdom of Champa.
The citadel could be, therefore, found in many ancient bibliographies. Scholars who study the history of Champa kingdom have done their utmost to explore the vestiges of the citadel.
Until the 21st century, it seems that all findings have brought no results. In 1933, when having the book entitled “An Introduction to An Nam and Champa studies” (Introduction à 1' étude de 1' Annam et du Champa) published, the French archaeologist, J.Y. Claeys, said it was a pity the citadel had been completely destroyed. Finding out the vestiges of the citadel, thus, seemed a hopeless task.
Fortunately, the construction in Binh Lam hamlet unearthed ramparts of an ancient citadel. Archaeologists all agreed these were remaining vestiges of Thi Nai citadel.
The citadel has many names. When describing the Chiem Thanh port at the end of the 13th century, Chinese historical documents said, “the north port is next to the sea and there are five small ports nearby connecting with Dai Chau. A mountain is in the south-east, the west is the Go (wood) citadel.”
The north port was called Cach Thu, an important port in Dai Chau; the south-eastern mountain was believed to belong to Trieu Chau mountain ranges; and the Go citadel was Thi Nai.
In the 13th century, the Champa army fought against the invasion of Mongol forces. In late 1282 A.D, Mongol troops of the Yuan Dynasty under General Sogetu (Sodu) invaded Champa and occupied Thi Nai.
In early 1284, Sogetu withdrew his troops from Champa kingdom and moved to the northern area. The troops then joined attacks on Dai Viet in 1285; however, the assaults were unsuccessful and Sogetu was also killed in an attack.
According to historical documents, the Dai Viet army assisted the Champa people in the war against the invasion of Mongol troops. The second anti-Mongol resistance war taking place in 1285 protected not only the whole country but the Champa kingdom from the invasion of Mongol troops.
The remains showed the citadel was built on an area lying between two branches of Kon River, that is Cau Dun and Go Thap Rivers. The rectangle-shaped citadel had a length of 1,300 metres and a width of more than 600 metres.
The most obvious vestige that could be found is in the northern area where the rampart was built along the Go Thap River.
The rampart in the south ran along the Cau Dun River. Its remains are a high strip of land whose surface is about 15-20 metres in width.
In the east, the remaining vestiges are only series of mounds on which bricks were lying in disorder. There was also a 30-metre trench outside, connecting Go Thap and Cau Dun Rivers.
The rampart in the west is only a strip of land mixed with broken bricks and it has a width of 4-6 metres.
The area in the citadel now becomes rice fields. When cultivating the land, farmers often saw Cham broken bricks and tiles. Alongside these, many mounds were found there. They are believed to belong to the foundations of ancient buildings.
Binh Lam tower located in the east is also one of vestiges of Thi Nai citadel.
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