Hi,
Definitely made in Thailand, with the Ramakien (Ramayana) figure in the center, likely mid 20th century. The mark is unusual, probably a maker's mark, nothing about the silver content. Genuine Thai silver is usually marked .925 or Sterling, or the Thai-language equivalent. Fake Thai silver is often marked that way as well. You would need to test your box, or have it tested, for silver content.