Omar Khayyam was a Persian polymath, mathematician, philosopher, astronomer, physician, and a celebrated poet. He was acknowledged as the author of the most important treatise on algebra before modern times. Omar Khayyam has written about a thousand four-line verses or quatrains. He was invited to come to Isfahan where he produced a new calendar called, Jalali calendar – it was adopted in 1075 by Malik-Shah (then, a ruler of Iran).