The Vietnamese are based on various dynasties in Vietnam before the European colonization. Historically, they were known as one of the few nations who repelled the Mongol invasion in the 13th century. This is mostly attributed to the resistance of the Vietnamese army that mostly consisted of peasants and volunteers that were quickly deployed in the battlefield to resist against enemy invasions. To reflect on the Vietnamese peasant army, they get free Conscription. The Vietnamese were also masters of guerilla warfare, using the Vietnamese jungle and cliffs as their advantage for traps and striking their enemies through the shadows of the Vietnamese jungle. Therefore, they have a unique upgrade for the Elite Skirmisher, the Imperial Skirmisher, which is available as a team bonus for Vietnamese allies.
The Vietnamese were known to be skilled in archery, and one of their known bows was made of rattan, a light-weight wood which was historically used to make armors and shields. This is why the Vietnamese gain extra HP for their Archery Range units and their unique unit, the Rattan Archer is an archer with high pierce armor. The Vietnamese were also known to breed elephants that were larger than most other elephants in the region, and deploy them in battle, which is why their unique technology gives extra HP to their Battle Elephants.
Even though the Vietnamese have resisted the Ming Dynasty's occupation and overthrew the Ming rulers in Vietnam, China had a strong influence in the region that shaped the Vietnamese culture. To reflect on China's influence, their unique technology, Paper Money, is team-based and grants each Vietnamese ally gold. Finally, the Vietnamese relied on peasant spies and infiltrators to locate enemy camps in order to setup surprise ambushes in the enemy camps which is why enemy Town Centers are revealed in the start of the game.
The Vietnamese are an archer civilization with strong emphasis of team support, and their foot archers are excellent soldiers, getting additional HP as well as every upgrade there is. Additionally, their unique unit and team bonus are both foot archers, making the Vietnamese able to pick from a wide variety of different units there. Their infantry and cavalry both miss Blast Furnace, and the latter is especially shallow with other key upgrades such as Husbandry and Hussar missing. Their Battle Elephants, however, get additional HP out of Chatras and have good defensive capabilities. The siege units are overall weak. Their navy is fair, but the Fast Fire Ship and Shipwright are missing. Their Monks rank below average as well. The defensive structures are overall good, but the lack of Masonry and Architecture is not helping. Their economy is good and especially suited for team games with Paper Money, but the lack of early game economic bonuses make the Vietnamese vulnerable to rush strategies.
In-game, Vietnamese units anachronistically speak modern Vietnamese, not Middle Vietnamese spoken during the feudal era (e.g. "heaven" is pronounced "trời" instead of "blời", spelled with phonetic elements 巴+例 (ba + lệ) in Nôm script).
When playing a random map game against the computer, the player may encounter any of the following Vietnamese AI characters:
Dinh Bo Linh (Đinh Bộ Lĩnh; 924–979): Vietnamese emperor from 968–979, first independent ruler of a unified Vietnam since its liberation from Southern Han Chinese control by Ngo Quyen. Emerged victorious after the chaotic "Anarchy of the 12 Warlords" period.
Le Dai Hanh (Lê Đại Hành; 941-1005): Became Emperor of Vietnam after the Dinh queen deposed her six-year-old heir of Dinh Bo Linh and trusted Le Dai Hanh to save the country. He successfully defended Vietnam from Song dynasty invasions.
Le Thai To (Lê Thái Tổ; 1384-1433): Real name was Le Loi, Emperor of Vietnam from 1428-1433, first emperor of the Later Le dynasty which would remain in power for over 300 years. He came to power via the Lam Son uprising against Ming Chinese rule.
Le Thanh Tong (Lê Thánh Tông; 1442-1497): Later Le Emperor of Vietnam from 1460-1497; he lead Vietnam through prosperous times and military successes against foreign threats. He also reformed the empire's legal system.
Ly Nam De (Lý Nam Đế; 503-548): Vietnamese king from 544-548; first ruler of the Early Ly dynasty. Originally a regional leader within the Chinese Liang Dynasty's administration of northern Vietnam, he resigned, and with local forces, rebelled to establish his own kingdom.
Ly Nhan Tong (Lý Nhân Tông; 1066-1128): Vietnamese Emperor from 1072-1128; a ruler of the Later Ly dynasty. He established Confucianism as the state philosophy; created schools of Confucian learning.
Ly Thai To (Lý Thái Tổ; 974-1028): Vietnamese Emperor from 1009-1028; the first of the Later Ly dynasty. From an orphan raised by monks he rose to head of imperial guards, elected by the entire country after the previous emperor died and none of his childen wanted the throne.
Ngo Quyen (Ngô Quyền; 897-944): Vietnamese King from 938-944 who rose to power after defeating Southern Han Chinese forces at the Battle of Bach Dang River in 938. His reign was marked by chaos and unrest, however, and his death was followed by the "Anarchy of the 12 Warlords" period.
Phung Hung (Phùng Hưng; 761-802): Mounted a rebellion against the Chinese Tang Dynasty in 791, becoming the de facto ruler over the region from 791-799. The Tang Dynasty still officially laid claim to the region.
Tran Anh Tong (Trần Anh Tông; 1276-1320): Vietnamese emperor of the Tran dynasty; ruled from 1293-1314. His reign was notable for relative peace and prosperity, upholding a détente with the Mongol Yuan Dynasty. Son of Tran Nhan Tong.
Tran Nhan Tong (Trần Nhân Tông; 1258-1308): Vietnamese emperor of the Tran dynasty; ruled from 1278-1293. He presided over the repulsion of invading Yuan Dynasty forces on land and at sea. Father of Tran Anh Tong.
Tran Thai Tong (Trần Thái Tông; 1218-1277): Vietnamese Emperor from 1226-1258; the first of the Tran dynasty. He used guerrilla warfare tactics against the first invasions of Vietnam by Yuan Dynasty forces. Grandfather of Tran Nhan Tong.
Alongside the Berbers, the Vietnamese are the only civilization that technically offers more than one team bonus (the Imperial Skirmisher, revelation of enemy positions, and a 500 gold tribute unique technology).
One of their unique technologies, Paper Money, is likely based on Ho Quy Ly's monetary reform in the 1400s, where he replaced metal coins with paper money as the mean of transaction.
The user interface of the Vietnamese civilization features a dragon in a distinctively Le Dynasty style. The two women with swords are likely a reference to Trưng Sisters, who started the very first uprising in Vietnam against Chinese overlords (year 40 to 43 AD), their martyrdom inspired countless Vietnamese throughout history to fight for Vietnam's independence.
Despite the Vietnamese using the Southeast Asian architecture set, Vietnamese architecture in real life strongly resembles Chinese architecture (or East Asian in Age of Empires II's parlance) due to China's strong cultural influence in Vietnam throughout medieval Vietnam's history. This will be rectified in the Definitive Edition.
The Vietnamese wonder, But Thap Temple, is such a Vietnamese architecture's sample.
According to the developers, the use of Southeast Asian architecture for the Vietnamese is supposed to reflect on the Dai Viet and Champa kingdoms in South Vietnam.
However, developers' explanation does not satisfactorily address the issue of historical anachronism. The Vietnamese campaign took place during the Fourth Chinese Domination (1407-1427), and the post-Trần-Hồ's Dai Viet then did not include the majority of Champa territories; not until Lê Lợi's grandson Tư Thành would conquer two Champa principalities and reduce the third one to a vassal tributary. Even after the conquest, Vietnamese who colonized conquered southern territories always built towns whose architecture is clearly based on Chinese architecture (for example, Hội An, built by Vietnamese, in former Champa lands).