The Tabaqat-i-Nasiri accounts the historical events that happened during the time of Slave dynasty of Delhi in the early times. It gives a general history of Islam from the earliest times to A.D. 1259. The author, Minhaj al-Siraj Juzjani, was a migrant to India who enjoyed the patronage of the youngest son of Iltutmish, Sultan Nasir-ud-din Mahmud who ruled from 1246 to 1265. The Tabaqat-i-Nasiri was later translated by Major Raverty. According to the translator, Major Raverty, Tabaqat-i-Nasiri is the 'very thesaurus of the most varied...material'.

Minhaj al-Siraj Juzjani, whose full name was Abu Umar Usman ibn Muhammad al-Minhaj-e-Siraj al Juzjani, continued to hold these offices during the reigns of his successors but for a brief period when he stayed at Bengal. His chief patron, however, was Sultan Nasir-ud-din Mahmud in whose honour he named his work "Tabaqat-i-Nasiri" which concludes with an account of the events of the fifteenth year of his reign. Though Minhaj al-Siraj Juzjani relied heavily upon the works of the earlier writers, his account of the Delhi Sultanate is particularly useful for being a contemporary source of Indian History of the early Indo-Muslim period.

'Usman ibn Siraju-d din al Juzjani, was descended from a noble family of GhaznΠwhich had been displaced following the fall of the Ghaznivids. His father, Maulana Siraju-d din, was the Quazi of Muhammad Ghori's army in India. Minhaju-d Siraju-d came to India in 624 H. (1227 CE), and was appointed the Director of Firozi College in Uch. In 625 H. (August 1228 CE), he entered the service of the Sultan of Delhi, Shamsu-d din Altamish who was popularly known as Iltutmish. He resigned during the brief rule Raziya Sultana. But he was appointed Quazi of Delhi by her successor, Sultan Bahram Shah, in 639 H. (1241 CE). When the Sultan was slain and deposed later that year, he resigned and retired to Lakhnauti in Bengal. In 642 H. he returned to Delhi, and entered the service of Sultan Nasiru-d din Mahmud in 644 H (1246 CE). It is believed that he outlived by several years the Sultan, who died in 664 H. (1266 CE). The Tabakat-i Nasiri is dedicated to the Sultan, and extends to the fifteenth year of his rule (658 H., 1260 CE). Minhaj-i-Siraj was born in the year 1193, died after 1259. Minhaj's family originally belonged to Jurjan, on the northwest frontier of Ghor. Minhaj came to India at the age of 34. At that time, he was fully educated according to the standard of the time and had some experience of diplomatic mission. He came to the court of Nasiruddin Qubacha at Uchch, who appointed him a Quazi. After Sultan Shamsuddin Iltutmish had occupied Multan from the hands of Qubacha, Minhaj moved to Delhi.

At Delhi, Minhaj found a suitable atmosphere to show his intellect to flourish and he was positoned as the posts of Imam, Qazi and Khatib and performed his duties efficiently. He came in close acquaintance with the Sultans of Delhi, and occupied various posts like principal of Madrasas, Imam, Khatib, Qazi and Sadr-i-Jahan. While holding the office of Qazi of Delhi in the reign of Sultan Nasiruddin Mahmud he wrote his famous book Tabaqat-i-Nasiri, and dedicated it to the reigning sultan. In 1259 AD in his late sixties, he promises to continue his narratives further if health permitted him, but his hopes were not fulfilled. Either his life soon came to an end, or some portion of his book containing the history later to 1259 AD has not come down to posterity.

About the book Tabaqat-i-Nasiri
Tabaqat-i-Nasiri is a medieval text by Minhaj-i-Siraj. It is an important account for the reconstruction of the history of foundation of Muslim rule in Bengal. The history of the first fifty years of Muslim rule in Bengal is found only in this text. Tabaqat-i-Nasiri is the only authentic source for the history of Bengal from the conquest of Muhammad Bakhtiyar Khilji till 1259 AD, when it comes to an end. Other contemporary sources are a few inscriptions and coins. The Tabaqat-i-Nasiri is not only a up to date book about the Delhi Muslims at that time, it is important for two reasons. Primarily, the author had come to Bengal and stayed there for about two years collecting materials for his book .He also draws the political scenario at that time. Secondly, because he devoted a section (tabaqat) in his book in discussing the history of the foundation of Muslim rule in Bengal, he gave the pen- picture of the socio economic history of Bengal. Beside this particular section dealing with the Khalji, Maliks of Lakhnauti i.e.from Bakhtiyar to Ghiyasuddin Iwaz Khalji , this book also discussed the history of Bengal under Sultan Shamsuddin Iltutmish and his successors. He also devoted sections to the Shamsi Maliks, i.e. the nobles of Sultan Shamsuddin Iltutmish, some of whom acted as governors of Bengal. In fact the history of Bengal from the Turkish conquest up to 1259 AD is available only in the Tabaqat-i-Nasiri of Minhaj-i-Siraj.

Minhaj met Malik Izzuddin Tughral Tughan Khan at Kara in about 1242 and thence came to the capital of Bengal, Lakhnauti. He stayed in Bengal for about two years and witnessed some important events. He joined Tughan Khan in his wars against Orissa, and acted as a mediator between his patron (Tughan Khan) and Malik Tamar Khan Qiran, governor of Oudh when both were quarrelling among themselves for the possession of Lakhnauti. During his stay at the Bengal capital he collected information about Bakhtiyar Khilji's conquests from his surviving associates. He also utilised the information that he could collect from people at Delhi who took part in battles of the Delhi Sultans against the Bengal rulers.

In the Tabaqat-i-Nasiri, the author also gives an idea about the development of Muslim society in Bengal. He says that Bakhtiyar Khalji built mosques, madrasas and khanqahs in the capital, and the nobles also followed his example. Sultan Ghiyasuddin Iwaz Khalji also built mosque and madrasas, he also arranged lectures on Islamic subjects (tazkir), which was delivered by Muslim divines coming from Muslim cultural centers of Central Asia. One such Muslim divine was Jalaluddin son of Jamaluddin Ghaznavi who delivered lectures in the assembly hall of Sultan Ghiyasuddin Iwaz Khalji.