The Mongols in South-East Asia

By Bloodswan

The lands which we today know as Burma, Cambodia, Vietnam, Thailand and Indonesia, with their dense jungles, long rivers, exotic wildlife, insects and diseases were to become Khubilai Khan’s last efforts at expanding Mongol lands. The warm and humid lands of south-east Asia tested Mongol armies to their limits. These lands were the most unlike their own lands on the steppes of Asia far to the North. The challenges of a different climate, sea transport, environment and unfamiliar styles of warfare were most noticeable during these campaigns. In fact it was probably here where they faced their most difficult challenges.

The Mongols had fought everywhere from the steppes of Mongolia to the snowy forests of Russia, from the mountains in Korea to the deserts of Syria but it was in the jungles of south-east Asia were the Mongols were faced with conditions and factors that were the most unfamiliar to them. These factors, most notably the heat and humidity took their tole on the military. Dense jungles, tropical swamps and long rivers were not suited to Mongol styles of warfare and although the Mongol army was able to adapt they were essentially never in their element during any of their south-east Asian campaigns.

Uriyangkhadai and the march into Vietnam

In 1253 Khubilai Khan annexed the Chinese province of Yunnan in a successful out-flanking move against Song China. During this campaign the Mongols destroyed the Nanzhao kingdom based at it’s capital of Dali. The campaign itself was carried out by Uriangkhadai, the son of the famous Mongol general Subodai Bahadur.

In 1257 Uriangkhadai led another expedition into the lands that we now know as Vietnam. At the time of the campaign Vietnam was divided by two kingdoms. In the north was the kingdom of Annam with their capital at Hanoi and in the south was the Champa kingdom whose capital at the time was Vijaya.

The Mongol advance against the Annamese was so rapid and devastating that the king fled to an offshore island and in 1258 recognised Mongol authority over his kingdom by sending his son as a hostage to the Khan’s court.

War elephants and guerrilla warfare

It was not until 1273 that the King of Champa received a command to pay homage to the Khan. Recalling the fate of Annam, the king immediately sent a tribute of 20 elephants to the Mongol court. However in 1281 his successor, King Jaya Indravarman IV refused to continue paying this humiliating tribute.

Khubilai responded to this by sending one of his leading officals, Sodu on a sea expedition against the king. Commanding a force of 100 ships and 5,000 men, Sodu landed on the Champa coast, but the king withdrew to the mountains and a fierce guerrilla war prevented the Mongols from making any headway.

War elephants would have played a part in the battles. The Mongols had faced elephants before in Persia but not in the numbers they probably faced during their south-east Asian campaigns. In Vietnam elephants had an established military role. Vietnamese elephants carried only one warrior as well as a mahout. The elephants took an active role in the fighting themselves and were described as taking on foot soldiers and hurling them into the air and attacked with their tusks. Another important note to point out was that the Mongol cavalry was useless in the jungle. The elephants were much better suited to jungle fighting. An interesting development in the use of elephants was also used against Sodu. A two man crossbow was used on the back of the elephant and acted as a mobile artillery unit. This technique was used by the Champa against the Khmer empire in 1177.

The Champa had many fortified jungle fortresses, some with walls nine metres in height. The Mongols were forced to ask the Annam empire for assistance but the king Tran Thah-ton was not willing to allow a large Mongol force in his territory despite paying regular tribute to the Mongols. Soon the Annam kingdom also resisted against the Mongols.

The guerrilla wars continued to take their toll on the Mongols and soon pestilence broke out in the Mongol camp. This added to the unfamiliar troubles of heavy rainfall and stifling heat which caused a severe drop in Mongol morale. In the summer of 1285 the Mongols were defeated at the decisive battle of Siming where Sodu was killed.

The second campaign and the battle of Bach Dang

A second campaign into Annam was launched in 1286 and reached Hanoi the following year. The city was captured and the king fled once again. Not completely satisfied with his victory, the Mongol commander Toghon returned during the hot season of 1288.

After the Annamese captured a number of Mongolian settlements they had shortage of food and the Toghan found himself in a tight corner. Toghan had to split his army into two and retreat home. Bridges and roads were destroyed and attacks were launched by the Annamese. In early April a supply fleet led by Omar fled home along the Bach Dang river.

After evacuating civilians from the new capital of Thang Long, the Annamese decided to launch an offensive against the Mongolians in an estuary of the Bach Dang river. The Annamese general was Tran Hung Dao. He used the same tactic as a famous Vietnamese general had done several centuries before him against a Chinese invasion at the same location. He carefully planted stakes under the water at a chosen location and organised ambush parties along the river. The trap was now set.

Once the Mongols reached Bach Dang, some Annamese boats harassed the Mongols then fled. As the Mongols pursued thousands of boats ambushed them. Inflicted with a sudden and strong attack, the Mongols tried to withdraw to the sea in panic. Hitting the stakes, their boats were halted and many were sunk. At that time, a number of fire rafts quickly rushed toward them setting fire to several Mongolian vessels. Frightened, the Mongolian troops jumped down to get to the banks where they were dealt a heavy blow by a big army led by Tran Hung Dao. The Mongolian supply fleet was totally destroyed and Omar was captured.

At the same time another army led by Dai Viet made continuous attacks and defeated Toghan’s army on its route of withdrawal through Lang Son. Toghan risked his life making a short cut through forests to flee home.

The kings of Annam and Champa however realised the need to negotiate with the Mongols in order to escape further attack. Both kingdoms offered token tribute to Khubilai and submitted to Mongol authority. As both kings had anticipated though this simply meant that they were left alone.

The Mongol invasion of Burma

In 1271 the Yunnan government in Dali was used by Khubilai to demand tribute from the king of Burma, Narathihapate. Narathihapate, who was said to have 3,000 concubines, sent back the Yunnan ambassadors empty handed. In 1273 Khubilai sent more ambassadors along with a letter written by himself demanding tribute. This time however the ambassadors were killed over a dispute involving not taking off their shoes in the king’s presence. The Yunnanese convinced the Khan that only war would bring the kingdom of Burma under Mongol control.

Action was not taken until 1277 when an unwise raid by the Burmese into southern China made a response inevitable. Khubilai sent Nasir al-Din, son of his trusted retainer Saiyid Ajall into Burma with the objective of taking the capital Pagan.

The Mongols continued their advance until heat and exhaustion forced them to return to China. The Burmese king did not learn from his mistake and after further Burmese raids Khubilai sent his grandson Temur on a second campaign against Burma to kill the “insolent king”. The capital of Pagan was sacked and Narathihapate fled. Narathihapate was poisoned by his son, who later lost what was left of his kingdom to the Mongols in 1287 at the battle of Vochan.

Burma presented similar challenges to Vietnam and Marco Polo’s description of the battle of Ngasaungyyan actually compressed a decade of campaigning in Burma. In one of his accounts his mentions an encounter on the plain of Vochan between the Mongol cavalry and Burmese war elephants. The account described how 12,000 well equipped Mongol cavalry faced a Burmese army of 60,000 plus 2,000 elephants. The elephants were used by the Burmese differently to the Annamese and held between twelve to sixteen men upon wooden castles on their backs. The Mongol’s horses could not be made to go anywhere near the elephants so the Mongol general had them tied up to trees and the Mongols fought dismounted. From cover of the trees they fired volley upon volley of arrows into the vulnerable parts of the elephants until they were driven away. Once the elephants had been driven away the Mongols mounted their horses and attacked the Burmese infantry defeating them. After the battle the Mongol commander took some elephants back to Khubilai who included them in his armies. Despite the battle of Vochan being hard fought the capital Pagan fell with such ease that Polo jokes that Khubilai ordered his court jesters and jugglers to take Burma.

The Mongol invasion of Java

Of all the Mongol campaigns in south-east Asia, Java was the most far flung. The process began as it had in Burma and Vietnam with the Mongol envoy demanding tribute from Java’s ruler, king Kertanagara. The king responded by branding the ambassador’s face.

The invasion began in 1292 with a fleet sailing out from Daytoun (Quanzhou). The journey took several months and did not land in Java until 1293. The landing spot was near present day Rembang on Java’s north-east coast. The Mongol commander ordered half of his troops to proceed overland in a show of force whilst the rest of his troops would continue eastward by sea. The rendezvous point was at Surabaya.

The two armies joined up in May with the land party encountering little resistance. The reason for this was that the land had already been scarred by recent fighting. A Javanese rebel had overthrown and killed King Kertanagara. Kertanagara’s son-in-law Prince Vijaya was carrying on the struggle in the south of the country. This accounted for the absence of troops in the North of the country.

Hoping to use the Mongols to help him crush the rebels, Prince Vijaya sent ambassadors to the Mongol camp and ensured them that he would pay tribute which his late father-in-law had earlier refused. Vijaya sent supplies to the Mongol force that marched to his aid and despite encountering rebel resistance on their way Vijaya’s to assistance they were easily defeated. The Mongols fought a rebel army at Modjopait (Majapahit) where Vijaya had been holding out and drove them back into the jungle.

The Mongols finally moved against the rebel stronghold at the fortified town of Daha (modern Kediri) and destroyed their army. Prince Vijaya seeing that his enemies were destroyed became reluctant to reward the Mongols for their efforts. He made up an excuse so he could return to his capital and was escorted by a small group of Mongol soldiers. On the way back he slaughtered the Mongol soldiers and took back his tribute. The Mongols quickly sent an army against him but they were ambushed and the survivors forced back to the coast.

The Mongols after considering their precarious position (where they had no hope of reinforcements and were already suffering from four months of equatorial heat) sailed home. They took with them any prisoners they had caught, gold, silver and rhinoceros horn. Despite the booty the campaign was a failure for the Mongols. 3,000 men had perished during the campaign and even the treasures brought back could not save the Mongol commander from receiving 17 lashes and losing one third of his property.

The submission of Siam and the Khmer empire

The Mongol campaigns in Siam were vastly different from those of the others already mentioned. The land we know as Thailand today was at this time a number of separate states. King Ramkhamhaeng of Siam whose capital was at Sukhothai took a very different approach to the Mongol empire than his contemporaries in Burma and Java. The king of Siam actively sought good relations with Khubilai and negotiated a treaty of amity with the Yuan dynasty in 1282. He made a personal visit to China to see the khan shortly before his death in 1294.

To the north of Siam was the kingdom of Lan Na. It was ruled by King Mangrai whose capital was at Chiang Mai. A border dispute led to war in 1296 but an expedition carried out in 1301 ended in a Mongol disaster.

The only other kingdom not yet mentioned is that of the Khmers of Cambodia. This once glorious empire that built the wonderful temples, shrines and palaces of Angkor was already overrun by Thais. They had already taken Sukhothai from the Khmers in 1220 and made it their capital. Ramkhamhaeng played a master-stroke in this regard. Whilst the Mongols threatened to destroy their enemies in Burma and Vietnam and with his Northern opponent in Lan Na in a state of concern, King Ramkhamhaeng could prosper at the Khmer’s expense. His Mongol allies had no concern over his realm and if matters changed, he still had Lan Na as a buffer in the north. Angkor held out until 1431 when it was finally taken by the Siamese.

The end of Mongol expansion

The Mongol wars in the south-east of Asia marked the extent of the Mongol conquests. By this time the Mongol empire had split into various khanates with the most notable being the Il-khans of Persia, the Golden horde of Russia and the Jagadai khanate of central Asia. On top of this was the Yuan dynasty of China founded by Khubilai Khan. A series of wars between the khanates effectively ended Mongol expansion westward whilst the campaigns against Japan and in south-east Asia ordered under Khubilai ended eastward expansion of the Yuan Mongol-Chinese Empire. These campaigns were very costly and many ended without effectively achieving their goals.

The Mongol invasions of south-east Asia can be seen as the background for the wars that ended Mongol expansion and it can be said that it was these wars coupled with the failure in Japan that ended the Yuan dynasty’s formidable military reputation.


The Mongols by Stephen Turnbull
Genghis Khan and the Mongol conquests by Stephen Turnbull
Fighting ships of the Far East 2 by Stephen Turnbull
Various internet sources