Wareru, a commoner, seized the governorship of Martaban (Mottama) in 1285, and after receiving the backing of the Sukhothai Kingdom, he went on to declare independence from Pagan in 1287.
In 1295–1296, he and his ally Tarabya, the self-proclaimed king of Pegu (Bago), decisively defeated a major invasion by Pagan.
Wareru eliminated Tarabya soon after, and emerged as the sole ruler of three Mon-speaking provinces of Bassein, Pegu and Martaban c. 1296.
Although he may have been of ethnic Mon or Shan background, Wareru's greatest legacy was the establishment of the only Mon-speaking polity left standing after the 1290s.
The success of the kingdom helped foster the emergence of the Mon people as a coherent ethnicity in the 14th and 15th centuries.
They grew up in their native village, located about 100 km north of the provincial capital of Martaban (present-day Mottama in Mon State), then part of the Pagan Empire.
[2] When he was about 19,[note 3] c. 1272, Gadu took over his father's side business of trading goods with the Siamese kingdom of Sukhothai to the east.
[4] So when the king was far away on a military expedition in the south, the couple, with a load of gold and silver, and about 270 of their retainers and troops fled to Tagaw Wun.
[6] Michael Aung-Thwin states that the elopement story is probably "a trope" to link the early kings of Martaban and those of Siam, and may not be historical.
At the time, Pagan's forces were faring badly against the Mongol invaders, and vassal rulers throughout the country had become increasingly restless.
On the night of the wedding, while Aleimma's guards were drunk, Gadu's men killed them, and assassinated the governor.
In the south, the king's army never got past Pegu (Bago), which was headed by another warlord Akhamaman, and failed both times to take the town in 1285–86.
By 1287, a diplomatic mission led by his minister Laik-Gi had successfully secured Ram Khamhaeng's support.
[15] The king of Sukhothai acknowledged Gadu as a vassal king, and awarded the royal title of "Chao Fa Rua" (Thai: เจ้าฟ้ารั่ว, "Lord Fa Rua", [t͡ɕaːw˥˩ faː˥.ruːa˥˩]))[16] also reported in Mon and Burmese as "Binnya Waru" (Burmese: ဗညား ဝါရူး, [bəɲá wàjú]))[17] and Smim Warow (Mon: သ္ငီ ဝါရောဝ်).
Indeed, Wareru's immediate concern was not Kyawswa but Tarabya, who had gained control of both Pegu and Dala and their surrounding districts.
At Martaban, c. 1290/91,[note 10] Wareru commissioned a dhammathat (customary law book) to be compiled in Mon, the main language of his nascent kingdom.
[25] (The compilation was part of a wider regional pattern in which the former lands of the empire as well as its neighboring states produced legal texts modeled after Pagan's, between 1275 and 1317.
The two sides met at the border, and the two lords agreed to fight in single combat on their war elephants.
But he did not control other former Pagan territories farther south such as Tavoy (Dawei), Mergui (Myeik) and Tenasserim (Taninthayi).
[38] By 1298, Wareru felt strong enough that he sent a diplomatic mission to Yuan China to receive recognition directly from the Mongol Emperor.
[38] Because he left no male heir, his younger brother Gada succeeded with the title of Hkun Law.
[38] Wareru's greatest legacy was the establishment of a Mon-speaking kingdom, which enabled the preservation and continuation of Mon culture.
The older Mon kingdoms of Dvaravati and Haripunjaya (in present-day Thailand) had been subsumed into Tai states of Sukhothai and Lan Na by the end of the 13th century.
The Code was the basic law of the Mon-speaking kingdom until the mid-16th century when it was adopted by the conquering First Toungoo Empire.
[46][47] The Code was adapted into the later dhammathats of the successor states of the empire, including Ayutthaya Siam[48] and Restored Toungoo Burma.