Đại Việt is the name of Vietnam for the periods from 1054 to 1400 and from 1428 to 1804. Beginning with the rule of Lý Thánh Tông, the third emperor of the Lý Dynasty, until the rule of Gia Long, the first emperor of the Nguyễn Dynasty, it was the second-longest used name for the country after "Văn Lang".
History
Beginning with the rule of Đinh Tiên Hoàng, the country had been referred to officially as Đại Cồ Việt. The term "Việt" is the same as the Chinese word "Yue", a name in ancient times of various non-Chinese groups who lived in what is now northern/southern China and northern Việt Nam. In 1010 Lý Thái Tổ, founder of the Lý Dynasty, issued the "Edict on the Transfer of the Capital" and moved the capital of Đại Cồ Việt to Thăng Long and built the Imperial Citadel of Thăng Long where the Hanoi Citadel would later stand. In 1054, Lý Thánh Tông – the third Lý emperor – renamed the country Đại Việt. In 1149 the Lý dynasty opened Vân Đồn seaport in the modern north-eastern province of Quảng Ninh to foreign trade. Đại Việt is a strategic location. By invading Đại Việt, the Mongols would be able to bypass the Himalaya and drive deep into South East Asia. However, the Mongolians of the Yuan Dynastyinvaded Dai Viet three times and were defeated. The last battle, the Battle of Bach Dang, was a decisive defeat for the Mongolians. Dai Viet's perseverance thwarted Mongolian attempts to conquer South East Asia and prevented the third Mongolian invasion of Japan, as the Mongol navy was completely destroyed during Bach Dang. This became one the greatest victories in Vietnamese military history. In 1400, the founder of the Hồ dynasty, Hồ Quý Ly usurped the throne and changed the country's name to "Đại Ngưu", but his dynasty was overthrown by the invading Ming Empire who annexedĐại Ngu in 1407 for 20 years until 1427. The Ming renamed the area "Giao Chỉ ". In 1428, Lê Lợi, the founder of the Lê dynasty, liberated Giao Chỉ and restored the kingdom of "Đại Việt". The name "Đại Việt" came to end when the Nguyễn dynasty took power. The country's name was officially changed yet again, in 1804, this time to "Việt Nam" by Gia Long.
