During this era, correspondences between royal courts in Sri Lanka and mainland Southeast Asia were conducted in Pali, and grammars aimed at speakers of Sinhala, Burmese, and other languages were produced. The emergence of the term 'Pali' as the name of the language of the Theravada cannon also occurred during this era. While Pali is generally recognized as an ancient language, no epigraphical or manuscript evidence has survived from the earliest eras. The earliest samples of Pali discovered are inscriptions believed to date from 5th to 8th Century located in mainland Southeast Asia, specifically central Siam and lower Burma. These inscriptions typically consist of short excerpts from the Pali Canon and non-canonical texts, and include several examples of the Ye dhamma hetu verse. Surprisingly, the oldest surviving Pali manuscript was discovered in Nepal, in the form of four folios from the Cullavagga dated to the 9th Century. The oldest manuscripts from Sri Lanka and Southeast Asia date to the 15th Century, with few surviving examples. Very few manuscripts older than 400 years have survived, and complete manuscripts of the four Nikayas are only available in examples from the 17th Century and later. Pali was first mentioned in Western literature in Simon de la Loubère's descriptions of his travels in the kingdom of Siam. An early grammar and dictionary was published by Methodist missionary Benjamin Clough in 1824, and an initial study published by Eugène Burnouf and Christian Lassen in 1826 ("Essai Sur Le Pali, Ou Langue Sacree de La Presqu'ile Au-Dela Du Gange"). The first modern Pali-English dictionary was published by Robert Childers in 1872 and 1875. Following the foundation of the Pali Text Society, English Pali studies grew rapidly and Childer's dictionary became outdated. Planning for a new dictionary began in the early 1900s, but delays (including the outbreak of World War I) meant that work was not completed until 1925  T. W. Rhys Davids in his book "Buddhist India", and Wilhelm Geiger in his book "Pāli Literature and Language", suggested that Pali may have originated as a lingua franca or common language of culture among people who used differing dialects in North India, used at the time of the Buddha and employed by him. Another scholar states that at that time it was "a refined and elegant vernacular of all Aryan-speaking people".