Many scholars believe that the Thai script is derived from the Khmer script, which is modeled after the Brahmic script from the Indic family. However, in appearance, Thai is closer to Thai Dam script, which may have the same Indian origins as the Khmer script. The language and its script are closely related to the Lao language and script. Most literate Lao are able to read and understand Thai, as more than half of the Thai vocabulary, grammar, intonation, vowels and so forth are common with the Lao language. Much like the Burmese adopted the Mon script (which also has Indic origins), the Thais adopted and modified the Khmer script to create their own writing system. While in Thai the pronunciation can largely be inferred from the script, the orthography is complex, with silent letters to preserve original spellings and many letters representing the same sound. While the oldest known inscription in the Khmer language dates from 611 CE, inscriptions in Thai writing began to appear around 1292 CE.