598 – Brahmagupta was born.
665 – He was the head of the astronomical observatory at Ujjain, and during his tenure there wrote two texts on mathematics and astronomy: the Brahmasphutasiddhanta, and the Khandakhadyaka.
628 – Brahmagupta gave the first general solution of the quadratic equation.
– Brahmagupta was the first to use algebra to solve astronomical problems. It was through the Brahmasphutasiddhanta that the Arabs learned of Indian astronomy.
712-775 – The famous Abbasid caliph Al-Mansur founded Baghdad, which is situated on the banks of the Tigris, and made it a center of learning.
770 – The caliph invited a scholar of Ujjain by the name of Kankah. Kankah used the Brahmasphutasiddhanta to explain the Hindu system of arithmetic astronomy.
668 – Brahhmagupta died.