https://en.m.wikipedia.org/wiki/Southeast_Asia

Avrin May L. Benavente

After the dissolution of the crown colony following Japanese occupation during World War II, Malacca became part of the independent Malayan Union in 1957 AD, which evolved into the modern nation of Malaysia. Prior to the war, the surrounding region had seen the development of rubber as a commercial crop; after the war, rubber became Malacca's primary export, making the city again a major port. Dredging and the construction of seawalls has made the city accessible to deep-draft ocean-going freighters and container ships, and the building of a railroad and modern highways into the city has made it an important cargo terminus in the region once more.

Source: civilization.wikia.com
Marc Jan Louise C. Castro

 The Pagan Dynasty lasted until 1287 when a Mongol invasion destroyed the city. Ethnic Shan rulers, who established a political center at Ava, filled the ensuing political vacuum for a short time.
SOURCE: http://www.globalsecurity.org/military/world/myanmar/history-pagan.htm
Erin Louise A. Sasa

Modern historians stated that the secession of Sukhothai (also spelled Sukhodaya)^[2]> from the Khmer empire began as early as 1180 during the reign of Pho Khun Sri Naw Namthom who was the ruler of Sukhothai and the peripheral city of Si Satchanalai (now a part of Sukhothai Province as Amphoe). Sukhothai had enjoyed a substantial autonomy until it was reconquered around 1180 by the Mon people of Lavo under Khomsabad Khlonlampong.

Two friends, Pho Khun Bangklanghao and Pho Khun Pha Mueang revolted against the Khmer Empire governor of Sukhothai.^{[3]:195–196} Khun, before becoming a Thai feudal title, was a Tai title for a ruler of a fortified town and its surrounding villages, together called a mueang; in older usage prefixed by pho (พ่อ) "father",^[4] (comparable in sound and meaning to rural English Paw). Bangklanghao ruled Sukhothai as Sri Indraditya – and began the Phra Ruang Dynasty - he expanded his primordial kingdom to the bordering cities. At the end of his reign in 1257, the Sukhothai kingdom covered the entire upper valley of the Chao Phraya River (then known simply as Menam, "Mother of Waters," the generic Thai name for rivers.)

Traditional Thai historians considered the foundation of the Sukhothai kingdom as the beginning of their nation because little was known about the kingdoms prior to Sukhothai. Modern historical studies demonstrate that Thai history began before Sukhothai. Yet the foundation of Sukhothai is still a celebrated event.

Fall of Sukhothai
After the Battle of Sittaung River in 1583, King Naresuan of Phitsanulok (and crown prince of Ayutthaya) forcibly relocated people from the cities of Phitsanulok, Sukhothai, Phichai, Sawankhalok (Si Satchanalai), Kamphaeng Phet, Phichit, and Prabang to the Southern Central plain,^[8] due to the war with the Burmese and an earthquake. After crown prince Mingyi Swa of Burma died in single combat at Don Chedi in 1592, these cities were restored, but not as an independent kingdom, but as provinces within the Ayutthaya Kingdom.^{[citation needed]}

The city was built on an island surrounded by three rivers, The Chao Phraya, the Pa Sak and the Lopburi river that served as a natural barrier against invaders. Ayutthaya was connected to the Gulf of Siam about 100 kilometers South by the Chao Phraya river.

A number of palaces and many imposing temples were built. Architecture and art were influenced by neighboring empires as Sukhothai and Angkor, as well as China, Japan and several European countries. One of the most clear examples of foreign influence is the large Angkor style prangs like the ones of the Wat Ratchaburana and the Wat Chaiwatthanaram.

Foreign trade settlements

Ayutthaya was a center of international trade which brought a great deal of prosperity. As foreigners were not allowed to live on the island, several countries including Holland, Portugal and Japan built settlements just off the island.

Wars with rival empires

During the over four centuries of its existence many wars were fought with rival Kingdoms as Sukhothai, Burma and Angkor. In 1431 Ayutthaya invaded Angkor ending the Khmer empire that had dominated much of South East Asia for centuries. Halfway the 15^th century Sukhothai, the first independent Thai Kingdom had weakened and was unified with Ayutthaya.

Several wars were fought with Burma during the second half of the 16^th century. In 1569 the Burmese invaded Ayutthaya, captured the Royal Family and took them to Pegu (present day Bago) in Burma. A few decades later during the reign of King Naresuan, the Burmese were driven out and Ayutthaya regained its independence.

The reign of King Narai the Great during the second half of the 17^th century was a time of great prosperity. The King established a second capital of the Kingdom in Lopburi, where he built a new palace.

Fall of the Ayutthaya Kingdom

Finally the Ayutthaya Kingdom ended in 1767 when the Burmese invaded and destroyed the city. The city was not rebuild; instead the Thais moved their capital further South to Thonburi.

- DANIELLE MARIA B. COSTALES
REFERENCE: https://www.renown-travel.com/historicalsites/ayutthaya/history.html

There is no continuous knowledge of Srivijaya in Indonesian histories; its forgotten past has been recreated by foreign scholars. No modern Indonesians, not even those of the Palembang area around which the kingdom was based, had heard of Srivijaya until the 1920s, when French scholar and epigraphist George Coedès published his discoveries and interpretations in Dutch and Indonesian-language newspapers.^[6] Coedès noted that the Chinese references to "Sanfoqi," previously read as "Sribhoja," and the inscriptions in Old Malay refer to the same empire.^[7]

In 1918, George Coedès linked a large maritime state identified in seventh-century Chinese sources as Shilifoshih, and described in later Indian and Arabic texts, to a group of stone inscriptions written in Old Malay which told about the foundation of a polity named Srivijaya, for which Shilifoshih was a regular Chinese transcription. These inscriptions were all dated between 683 and 686, and had been found around the city of Palembang, on Sumatra. A few Hindu and Buddhist statues had been found in the region, but there was little archaeological evidence to document the existence of a large state with a wealthy and prestigious ruler and a center of Buddhist scholarship. Such evidence was found at other sites on the isthmus of the Malay Peninsula, and suggested that they may have been the capital of Srivijaya. Finally, in the 1980s, enough archaeological evidence was found in Southern Sumatra and around Palembang to support Coedès' theory that a large trading settlement, with manufacturing, religious, commercial and political centers, had existed there for several centuries prior to the fourteenth century. Most of the information about Srivijaya has been deduced from these archaeological finds, plus stone inscriptions found in Sumatra, Java, and Malaysia, and the historical records and diaries of Arab and Chinese traders and Buddhist travelers.^[8]

Srivijaya and by extension Sumatra had been known by different names to different peoples. The Chinese called it Sanfotsi or San Fo Qi, and at one time there was an even older kingdom of Kantoli that could be considered as the predecessor of Srivijaya.^[9] In Sanskrit and Pali, it was referred to as Yavadesh and Javadeh respectively. The Arabs called it Zabag and the Khmer called it Melayu. The confusion over names is another reason why the discovery of Srivijaya was so difficult.^[9] While some of these names are strongly reminiscent of the name of Java, there is a distinct possibility that they may have referred to Sumatra instead.<sup>[10]

Source:
http://www.newworldencyclopedia.org/entry/Srivijaya
-Roberto C. Arzadon II</sup>

The kingdom grew out of a small 9th-century settlement at Pagan (Bagan) by the Mranma (Burmans), who had recently entered the Irrawaddy valley from the Kingdom of Nanzhao. Over the next two hundred years, the small principality gradually grew to absorb its surrounding regions until the 1050s and 1060s when King Anawrahta founded the Pagan Kingdom, for the first time unifying under one polity the Irrawaddy valley and its periphery. By the late 12th century Anawrahta's successors had extended their influence farther to the south into the upper Malay peninsula, to the east at least to the Salween river, in the farther north to below the current China border, and to the west, in northern Arakan and the Chin Hills.^[2][3] In the 12th and 13th centuries, Pagan, alongside the Khmer Empire, was one of two main empires in mainland Southeast Asia.^[4]

The Burmese language and culture gradually became dominant in the upper Irrawaddy valley, eclipsing the Pyu, Mon and Pali norms by the late 12th century. Theravada Buddhism slowly began to spread to the village level although Tantric, Mahayana, Brahmanic, and animist practices remained heavily entrenched at all social strata. Pagan's rulers built over 10,000 Buddhist temples in the Pagan capital zone of which over 2000 remain. The wealthy donated tax-free land to religious authorities.^[5]

The kingdom went into decline in the mid-13th century as the continuous growth of tax-free religious wealth by the 1280s had severely affected the crown's ability to retain the loyalty of courtiers and military servicemen. This ushered in a vicious circle of internal disorders and external challenges by the Arakanese, Mons, Mongols and Shans. Repeated Mongol invasions (1277–1301) toppled the four-century-old kingdom in 1287. The collapse was followed by 250 years of political fragmentation that lasted well into the 16th century.^{[6][7]
Source:
https://en.m.wikipedia.org/wiki/Pagan_Kingdom}

-Fiona Louise Aika R. Hoyohoy

By the 7th century CE, Khmer people inhabited territories along the Mekong river -the world’s seventh longest river - from the delta to roughly the modern Cambodia-Laos border, plus the region between that river and the great Tonle Sap lake to the west and the area running along the Tonle Sap river (which runs from the lake to the sea, joining the Mekong in the delta). There were several kingdoms at constant war against each other, with art and culture heavily influenced by India due to long established sea trade routes with that subcontinent.