Trịnh lords in the context of "Đàng Ngoài"

The Nguyễn lords (Vietnamese: Chúa Nguyễn, 主阮; 1558–1777, 1780–1802), also known as the Nguyễn clan (Vietnamese: Nguyễn thị; chữ Hán: 阮氏), were Nguyễn dynasty's forerunner and a feudal noble clan ruling southern Đại Việt in the Revival Lê dynasty. The Nguyễn lords were members of the House of Nguyễn Phúc. The territory they ruled was known contemporarily as Đàng Trong (Inner Realm) and known by Europeans as the Kingdom of Cochinchina and as Kingdom of Quảng Nam (Vietnamese: Quảng Nam Quốc; chữ Hán: 廣南國) by Imperial China, in opposition to the Trịnh lords ruling northern Đại Việt as Đàng Ngoài (Outer Realm), known as the "Kingdom of Tonkin" by Europeans and "Kingdom of Annam" (Vietnamese: An Nam Quốc; chữ Hán: 安南國) by Imperial China in bilateral diplomacy. They were officially entitled, in Sino-Vietnamese, the Nguyễn Vương (chữ Hán: 阮王) in 1744 when lord Nguyễn Phúc Khoát self-proclaimed himself to elevate his status equally to Trịnh lords's title known as the Trịnh Vương (Vietnamese: Trịnh Vương; chữ Hán: 鄭王). Both Nguyễn and Trịnh clans were de jure subordinates and fief of the Lê dynasty. However, the de jure submission of the Nguyễn lords to the Trịnh lords ended in 1627 sparked the war between them.

While they recognized the authority of and claimed to be loyal subjects of the revival Lê dynasty, they were de facto rulers of southern Đại Việt. Meanwhile, the Trịnh lords ruled northern Đại Việt in the name of the Lê emperor, who was in reality a puppet ruler. They fought a series of long and bitter wars that pitted the two halves of Vietnam against each other. The Nguyễn were finally overthrown in the Tây Sơn wars, but one of their descendants would eventually come to unite all of Vietnam. Their rule consolidated earlier southward expansion into Champa and pushed southwest into Cambodia.

The Tây Sơn dynasty (Vietnamese: [təj ʂəːn]; Vietnamese: "Nhà Tây Sơn" or "Triều Tây Sơn", (chữ Hán: 朝西山; Chữ Nôm: 茹西山), officially Đại Việt (Chữ Hán: 大越), was an imperial dynasty of Vietnam. It originated in a revolt led by three peasant brothers with the surname Nguyễn, rebelling against the Lê dynasty, Trịnh lords and Nguyễn lords (no relation). The Tây Sơn would later be succeeded by the Nguyễn dynasty.

The Tây Sơn dynasty ended the century-long war between the Trịnh and Nguyễn families, overthrew the Lê dynasty, and united the country for the first time in 200 years. They acknowledged Qing suzerainty and gained recognition from the Qianlong Emperor as the legitimate rulers of Vietnam. Under the most prominent of the Tây Sơn brothers Nguyễn Huệ (Emperor Quang Trung) Vietnam experienced several years of relative peace and prosperity. But Quang Trung died relatively young at the age of 40 and his successor Cảnh Thịnh, aged 9, was unable to prevent civil conflict among the Tây Sơn court which allowed the last Nguyễn lord Nguyễn Ánh to retake the south of Vietnam, extinguish the Tây Sơn and establish the Nguyễn dynasty.

Gia Long (Chữ hán: 嘉隆) (Vietnamese: [zaː lawŋ] (North), [jaː lawŋ] (South); 8 February 1762 – 3 February 1820), born Nguyễn Phúc Ánh (阮福暎) or Nguyễn Ánh (阮暎), was the founding emperor of the Nguyễn dynasty, the last dynasty of Vietnam, which would rule the unified territories that constitute modern-day Vietnam until 1945.

A nephew of the last Nguyễn lord who ruled over south Vietnam, Nguyễn Ánh was forced into hiding in 1777 as a 15-year-old when his family was slain in the Tây Sơn revolt. After several changes of fortune in which his loyalists regained and again lost Saigon, he befriended the French Catholic Bishop Pierre Pigneau de Behaine. Pigneau championed Nguyễn Ánh's cause to regain the throne to the French government and managed to recruit volunteers however, that soon encountered difficulties. From 1789, Nguyễn Ánh was once again in the ascendancy and began his northward march to defeat the Tây Sơn, reaching the border with the Qing dynasty by 1802, which had previously been under the control of the Trịnh lords. Following their defeat, he succeeded in reuniting Vietnam after centuries of internecine feudal warfare, with a greater landmass than ever before, stretching from the Qing's borders down to the Gulf of Siam.

Cochinchina or Cochin-China (/ˌkoʊtʃɪnˈtʃaɪnə/, UK also /ˌkɒtʃ-/; Vietnamese: Đàng Trong (17th–18th centuries), Việt Nam (1802–1831), Đại Nam (1831–1862), Nam Kỳ (1862–1945); Khmer: កូសាំងស៊ីន, romanized: Kosăngsin; French: Cochinchine; Chinese: 交趾支那; pinyin: Jiāozhǐ zhīnà) is a historical exonym for part of Vietnam, depending on the contexts, usually for Southern Vietnam. Sometimes it referred to the whole of Vietnam, but it was commonly used to refer to the region south of the Gianh River.

In the 17th and 18th centuries, Vietnam was divided between the Trịnh lords to the north and the Nguyễn lords to the south. The two domains bordered each other on the Son River. The northern section was called Tonkin by Europeans, and the southern part, Đàng Trong, was called Cochinchina by most Europeans and Quinam by the Dutch.

Tonkin, also spelled Tongkin, Tonquin or Tongking, is an exonym referring to the area surrounding the Red River Delta of Northern Vietnam. During the 17th and 18th centuries, this term referred to the domain of Đàng Ngoài, under the control of the Trịnh lords, encompassing both the Northern and Thanh–Nghệ regions, north of the Gianh River at the 17.7th parallel. From 1884 to early 1945, the term referred to the French protectorate of Tonkin, which comprised only the Northern region, approximately north of the 20th parallel.

The Military of the Nguyễn dynasty (Vietnamese: Quân thứ; chữ Hán: 軍次) were the main military forces of the Nguyễn dynasty from 1802 to August 1945 when it was dismantled by the August Revolution. The Nguyễn military force was initially formed by Nguyễn Hoàng as a division of the military of the Revival Lê dynasty in 1558 starting out with 3000 soldiers. During this period it was the military forces of the domain of the Nguyễn lords and commonly fought the Trịnh lords who controlled northern Vietnam. During the Tây Sơn Rebellion it was expelled out most of the county by the Tây Sơn dynasty. After the exiled Nguyễn Phúc Ánh returned and defeated the Tây Sơn rebels he crowned himself as the Gia Long Emperor and the Nguyễn military became the national military of Vietnam.

During the French domination period it became two of the five indigenous guards of French Indochina and was turned into a collection police and ceremonial forces. While the Emperor was still nominally the supreme commander actual power fell in the hands of the French administration relegating the Emperor to a rubber stamp office. Following the abolition of the Nguyễn dynasty its military was also disbanded making the Vietnamese People's Army the new national military of Vietnam, which would be administered by the newly established Democratic Republic of Vietnam.

The Lê dynasty, also known in historiography as the Later Lê dynasty (Vietnamese: "Nhà Hậu Lê" or "Triều Hậu Lê", chữ Hán: 朝後黎, chữ Nôm: 茹後黎), officially Đại Việt (Chữ Hán: 大越), was the longest-ruling Vietnamese dynasty, having ruled from 1428 to 1789, with an interregnum between 1527 and 1533. The Lê dynasty is divided into two historical periods: the Initial Lê dynasty (Vietnamese: triều Lê sơ, chữ Hán: 朝黎初, or Vietnamese: nhà Lê sơ, chữ Nôm: 茹黎初; 1428–1527) before the usurpation by the Mạc dynasty, in which emperors ruled in their own right, and the Revival Lê dynasty (Vietnamese: triều Lê Trung hưng, chữ Hán: 朝黎中興, or Vietnamese: nhà Lê trung hưng, chữ Nôm: 茹黎中興; 1533–1789), in which the emperors were figures who reigned under the auspices of the powerful Trịnh family. The Revival Lê dynasty was marked by two lengthy civil wars: the Lê–Mạc War (1533–1592) in which two dynasties battled for legitimacy in northern Vietnam and the Trịnh–Nguyễn Wars (1627–1672, 1774–1777) between the Trịnh lords in North and the Nguyễn lords of the South.

The dynasty officially began in 1428 with the enthronement of Lê Lợi after he drove the Ming Chinese army from Vietnam. The dynasty reached its peak during the reign of Lê Thánh Tông and declined after his death in 1497. In 1527, the Mạc dynasty usurped the throne; when the Lê dynasty was restored in 1533, the Mạc fled to the far north and continued to claim the throne during the period known as Southern and Northern Dynasties. The restored Lê emperors held no real power, and by the time the Mạc dynasty was finally eradicated in 1677, actual power lay in the hands of the Trịnh lords in the North and Nguyễn lords in the South, both ruling in the name of the Lê emperor while fighting each other. The Lê dynasty officially ended in 1789, when the peasant uprising of the Tây Sơn brothers defeated both the Trịnh and the Nguyễn, ironically in order to restore power to the Lê dynasty.