Sri Naw Nam Thum
Sri Naw Nam Thum was a Tai monarch mentioned in the Wat Si Chum Inscription as the ruler of Mueang Chaliang–Sukhothai during the late 12th to early 13th century. Meanwhile, the lineage of Si Inthrathit, the inaugural monarch of Sukhothai, is recorded to have descended from the indigenous royal house of the Padumasuriyavamsa; etymological analysis suggests that the Sri Naw Nam Thum line may have traced back to the Tai-speaking people of the Red River Basin in present-day Vietnam, who subsequently migrated westward to the Pasak Basin and later extended their cultural and political influence toward the Monic Mueang Chaliang and Sukhothai. This group, known as the Tai Lueang, maintained close dynastic affiliations with the, who inhabited the city-states of and. However, following the annexation of their polities by the Lan Na Kingdom during the reign of King Tilokaraj, both the Tai Lueang and Tai Kao were assimilated by the Tai Yuan, who imposed their cultural norms, language, and identity upon these groups. Consequently, the distinct ethnic and cultural identities of the Tai Lueang and Tai Kao gradually dissolved into the broader Tai Yuan sociocultural sphere.
Sri Naw Nam Thum is generally regarded as a nobleman from Mueang Chaliang who consolidated political and military power through his son, Pha Mueang, ruler of Mueang Rat, who was married to, a princess under the suzerainty of the Angkorian monarch Jayavarman VII. Sri Naw Nam Thum is believed to have succeeded the weakened ruler Rajadhiraj II of the Mon Haripuñjaya dynasty, likely at the beginning of the 13th century. This narrative, when considered alongside the aforementioned etymological analysis, aligns with the hypothesis advanced by the Japanese scholar Tatsuo Hoshino, who located the Cān Bàn Kingdom—a polity that had maintained an alliance with Chenla through royal intermarriage since the 7th century—in the upper Pasak Basin, the region in which Mueang Rat was located, identifying it as a Tai-speaking kingdom.
In 1219—though certain sources suggest as early as the late 1170s—Sri Naw Nam Thum, together with his son Pha Mueang, launched a southern campaign and successfully seized Sukhothai, overthrowing the preceding Mon ruler, E Daeng Phloeng. Following this conquest, Sri Naw Nam Thum governed as a dual monarch over both Sukhothai and Chaliang. His reign, however, was short-lived; he was subsequently deposed by an usurper, Khom Sabat Khlon Lamphong, who is thought to have originated from Lavo—a polity that had fallen under the influence of the Angkorian Mahidharapura dynasty by the 1180s—or to have been a relative of Sri Naw Nam Thum with close affiliations to Lavo. The Mahidharapura dynasty is recorded to have captured Xiū Luó Fēn of the Xiān in the Phraek Si Racha region, located south of Sukhothai, and re-established it as Chen Li Fu during the same period.
After the deposition of his father, Pha Mueang allied with Bang Klang Hao and later recaptured the territories in 1238. Bang Klang Hao subsequently ascended the throne as ruler of Sukhothai–Chaliang under the regnal title Si Inthrathit. Si Inthrathit married, a daughter of Sri Naw Nam Thum.