A Mongolian manuscript book, written in Tibetan, of the Guhyasam'aja tantra (The Tantra of the Secret Assembly), an advanced (esoteric) religious text of the Gelug School of Vajrayana Buddhism. Indo-Tibetan-style books, such as this one, consist of long, unbound sheets sandwiched between wooden covers, that are stored wrapped up with a cloth and secured with a belt.

This book is missing the original covers, wrapping cloth and four leaves, as it would have originally consisted of 18 leaves. The compact dimensions of this particular manuscript suggest that it was intended for private use, with the smaller size allowing for easy portability.

The pages are made from paper that has been primed with a glossy black surface, created by applying a mixture of soot and hide glue, then polishing. Each block of text is enclosed within a white, double-lined border with every line of text written in a different colour, following a repeated sequence. This multicoloured script is achieved using inks made from pigments derived from finely ground precious substances of religious importance, known as the Nine Treasures or Nine Jewels. These include lapis lazuli, pearl, copper, gold, silver, coral, turquoise, mother of pearl and steel.