Folding-book manuscript
Folding-book manuscripts are a type of writing material historically used in Mainland Southeast Asia, particularly in the areas of present-day Myanmar, Thailand, Laos and Cambodia. They are known as parabaik in Burmese, samut thai in Thai or samut khoi in Thai and Lao, phap sa in Northern Thai and Lao, and kraing in Khmer. The manuscripts are made of a thick paper, usually of the Siamese rough bush ("khoi" in Thai and Lao) tree or paper mulberry, glued into a very long sheet and folded in a concertina fashion, with the front and back lacquered  to form protective covers or attached to decorative wood covers. The unbound books are made in either white or black varieties, with the paper being undyed in the former and blackened with soot or lacquer in the latter. Myanmar. Along with paper made from bamboo and palm leaves, "parabaik" were the main medium for writing and drawing in early modern Burma/Myanmar. There are two types of "parabaik": historically, black "parabaik" () were the main medium of writing while the white "parabaik" () were used for paintings and drawings. The extant black "parabaik" consist of works of scientific and technical importance like  medicine, mathematics, astronomy, astrology, history, social and economic commentary, music, historical ballads, fiction, poetry, etc. The extant white "parabaik" show colored drawings of kings and court activities, stories, social customs and manners, houses, dresses, hair styles, ornaments, &c. The majority of Burmese chronicles were originally written on "parabaik". A 1979 UN study finds that "thousands upon thousands" of rolls of ancient "parabaik" were found (usually in monasteries and in homes of private collectors) across the country but the vast majority were not properly maintained. Thailand. The use of "samut khoi" in Thailand dates at least to the Ayutthaya period (14th–18th  centuries). They were used for secular texts including royal chronicles, legal documents and works of literature, as well as some Buddhist texts, though palm-leaf manuscripts were more commonly used for religious texts. Illustrated folding books were produced for a range of different purposes in Thai Buddhist monasteries and at royal and local courts. They served as handbooks and chanting manuals for Buddhist monks and novices. Producing folding books or sponsoring them was regarded as especially meritorious. They often, therefore, functioned as presentation volumes in honor of the deceased. A commonly reproduced work in the "samut khoi" format is the  legend of Phra Malai, a Buddhist monk who travelled to heaven and hell. Such manuscripts are often richly illustrated. Cambodia. The paper used for Khmer books, known as "kraing", was made from the bark of the mulberry tree. In what is now known as Cambodia, "kraing" literature was stored in pagodas across the country. During the Cambodian civil war and the subsequent Khmer Rouge regime of the 1960s and 1970s, as many as 80% of the pagodas in Cambodia were destroyed, including their libraries. In Cambodia, only a tiny fraction of the original "kraing" of the Khmer Empire have survived