A Brief Introduction to Black Tatar is rich in content, which introduces the main characters, geography and climate, grazing and hunting methods, language, calendar, occupation, official system and customary law, customs and habits, taxation, merchants, troops, weapons, methods of warfare, marching positions, and the names of the countries they belong to and conquer. Some parts are recorded in detail and have high historical value. It is a valuable material for studying Mongolian history in the first half of13rd century. The word "Hui" is mentioned in many places in the book, such as "Hui skills are superb, especially siege", "Yan Jingcheng studied Hui characters and translated by Tartars", and "After Tartars, only paid silver and sold themselves", which are the most involved in the works of the Song Dynasty after Bitan. Song people called Mongolia black Tatar, which is different from the white Tatar in the south of the desert (that is, Wang Jiabu), hence the name. Peng and Xu went to Mongolia on 1232 and 1235 ~ 1236 respectively. Peng Daya was the first to write the manuscript. When he came back with the ambassador, he cross-referenced his knowledge and experience with Peng Daya's manuscript, took Peng's manuscript as the final version, and wrote his different records as sparse notes under various related matters to synthesize a book.