Ghaznavid Empire

Al-Biruni's own measurements, documented in the Determination of the Coordinates of Locations for Accurately Measuring the Distances Between Places, were widely accepted by his contemporaries and later scientists.

al-Biruni's later life and works were shaped by Mahmud Ghazni, sultan of the Ghaznavid Empire from 998 to 1030.

Mahmud was a terrific military leader, reputed never to have lost a battle, who dramatically extended his unstable empire.

Among the lands he conquered was al-Biruni's native Khwarizm.

If the statement of mathematicians is correct, it is a strange commentary upon the era in which we live, the age of precision, that the calendar which contents us should be less accurate than that of the old astronomer of Khorasan eight centuries ago.

The province of Khorasan, situated in northeastern Persia, and which has been characterized with more flippancy than truth as being, in Omar's day, a half-barbarous province, was one of the richest divisions of the kingdom at that time and formed the nucleus of the expanding empire conquered by the Seljuk Turks, Togrul Beg and his brother and lieutenant Shakir from the Ghaznavids about the middle of the 11th century of our era.

Shakir died in 1060 AD and Togrul three years later and was succeeded by Alp Arslan, his nephew, under whom and his successor, Malik Shah, the empire attained the highest degree of prosperity and splendor.

Khorasan, aptly called the Land of the Sun by reason of its mild climate and generally fertile and productive soil, was the very heart of this material and intellectual uprising, and Nishapur, its largest city, the birthplace of the poet, was one of the great cities of the Orient, the center of a prosperous activity well named the Gateway of the East, lying as it did directly upon the caravan route from India.