The history of modern Thailand, until recently called Siam, begins with the Chakri dynasty. Each king of the dynasty has taken the name Rama. While the story of Rama was widespread, the first Chakri king, Rama I, composed a long poetic version in 1782, the year that Bangkok was founded. (His successor, Rama II, composed a shorter version.) Rama I also commissioned the building of a temple as part of the Grand Palace complex. This Temple of the Emerald Buddha contains Thailand's most important Buddha image. Surrounding the central building of the temple is a four-sided gallery. Rama I directed the walls of this gallery to be painted with scenes of the avatars of Vishnu, including paintings portraying the entire Ramakien of Rama I. Thai mural paintings are not frescoes, in which the pigment is mixed into wet plaster. Instead, the painting is done on a dry surface. The technique is not ideal for Thailand's humid environment, and the paintings have suffered. They have been repaired every fifty years since their creation (most recently at the direction of the current king, Rama IX, in 1982). Art preservation in Thailand differs from western custom, and it is very difficult to say how similar the current paintings are to those originally commissioned. In a sense it does not matter, as illustrating the Ramakien has itself become a traditional art form.
The Ramakien of Rama I is not in any sense a direct descendent of the Valmiki Ramayana recorded in Sankrit. It is simply another of the many versions of the story. In addition to the Sanskrit tradition, it is influenced by Sri Lankan, Khmer, Burmese, and many other versions. Sometimes names are different. Rama's nemesis in the Ramayana is Ravana, in the Ramakien it is Tosakan. Similarly, in the Sanskrit account Rama's loyal brother is Lakshmana, in the Thai account he is Lak. Other differences are more significant. Emphases differ; the troubling story of Rama's relationship with the monkey king Sugriva in the Ramayana is gone from the Thai version. In fact, in the Ramakien the loyal Hanuman is the monkey king, and Sukhreep, the equivalent of the Ramayana's Sugriva, is one of his captains. Still, for all the differences between the Sanskrit Ramayana and the Thai Ramakien, the synopses offered here will help to contextualize the passages of the Ramayana that you read.