The affinity between the scripts of Laos and other regional writing has been recognised since the first historial studies on the country, conducted at the end of the nineteenth century.
Father Schmitt, who in 1898 published a body of 31 stele inscriptions presented as "thai", had little difficulty associating documents found in northern Thailand, in particular at Sukhothai and Chiang Mai, with a body of six epigraphic texts discovered in Luang Prabang. He noted, however, a peculiarity : while two of those inscriptions follow what is called the Sukhodaya (Sukhothai) script, the other four, more recent, are graphically linked to a Burmese model.
At the time, the fact that the Lao had used various types of script caused no surprise. (…)

Post-Scriptum :

in : "Written Cultures in Mainland Southeast Asia", Masao Kashinaga (ed.), Senri Ethnological Studies, n°74, 2009. pp.33-49.