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 (ไทเลือง), maintained close dynastic affiliations with the Tai Kao, who inhabited the city-states of Nan and Phrae. 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.