Al-Bayrouni was dedicated to study, trying to study older works in the languages in which they were written.

This required him to learn several languages, and indeed he acquired a good standard in Persian, Greek, Syriac and Sanskrit, in addition to his excellent knowledge of Arabic.

This enabled him to develop a better understanding of different cultures. He also met a number of the most distinguished scholars of his time, most notably Ibn Sina, the great physician. He published a number of books which earned him acclaim as a scholar.

He then studied astronomy and devoted much time to observing celestial bodies. His observations enabled him to write several books and develop a new idea to measure the circumference of the earth.

He was able to formulate a rule that came to be known after him, which enabled him to calculate the earth diameter. He was able to develop a scientific method to determine the direction of Makkah from any place on the globe. He relied mainly on research and experiment as the main methods of acquiring knowledge. He warned strongly against blind following of what is universally accepted as true. He also emphasized the need for a scholar to be humble, recognizing his limitations, and to free himself of the hold of preconceived ideas, because they could easily impede his research.

Al-Bayrouni accompanied Sultan Mahmood of Ghaznah on his expeditions into India. For the Sultan believed that scholars and literary figures have an important role in such engagements. Al-Bayrouni accompanied him no less than 13 times, spending in India nearly forty years. His role was to spread Islamic knowledge, and to acquire whatever he could of Indian scholarship, together with information about the social and religious setup in the subcontinent.

Needless to say, with his undoubted gifts and talents, Al-Bayrouni was able to learn about India more than anyone else.

Al-Bayrouni wrote a large number of books, said to be 180, including 35 treaties on pure astronomy, but many of his books have been lost. What survives remains mostly in manuscript form in different libraries. However, efforts have been made recently to publish his works. Many of his books are on topics related to astronomy and geometry, testifying to his very high achievement in mathematics. Some of his books explain a number of important rules of applied astronomy.

However, his most important book in this field is the one known as Al-Qanoon Al-Masoudi, which he dedicated to Sultan Masoud.

When Sultan Mahmood took Al-Bayrouni with him on his Indian expeditions, he wanted him to study the country, debate with its scholars and philosophers, learn the main Indian language and read Indian poetry, and acquire a profound insight into their society and their scholarly methods. Al-Bayrouni applied himself to the task with his customary diligence.

The result was a famous book he wrote under the title Tahqeeq Ma Lil-Hind Min Maqoolah, or Verification of What Is Said about India. It is a comprehensive book that covers a wide area.

The book, which came to be known as the History of India, was not the first to be written about India and its inhabitants. But it outshines all that was written before it for its comprehensive outlook and rich subject matter. It is clear that the book was written over a long period of time, and Al-Bayrouni finalized it when he was in his mid-fifties, at the height of his scholarly maturity.

The book includes 80 chapters addressing a variety of subjects, such as beliefs and laws, worship, the caste system, methods of writing, calligraphy, poetry and linguistics, the Indian literary heritage, geography, Indian astronomy, calendar, months, years and days, etc. Al-Bayrouni aimed to present the facts without trying to offer any argument for or against what he recorded.

He describes his method saying: “The book offers no room for debate or argument so as to require me to record the other point of view and discuss what deviates from the truth.

“It is a descriptive work in which I record what I see and know. I may add what the Greeks have or say on certain points for the sake of comparison.”

The book was published by a German scholar in 1887, writing in his introduction: “This is an invaluable book which is rich in highly important information about India that most of Al-Bayrouni’s contemporaries were unaware of, and that remained unknown to Europeans until recently.”