He was simultaneously a geographer, a mathematician, and a philosopher. He translated Ptolemy's book on geography in 830 AD and drew up a large map of the world. He followed the latitudes described by Ptolemy but added the Muslim-conquered states in his book of geography. He also drew up under the orders of al-Ma'mun a large map of population and geography called Surat al-Ard . This map was accepted and followed as a model by western geographers while drawing the map of the world. In this map the earth was divided into seven zones in accordance with its climatic changes. By following his principles, the famous astronomers, Al-Farghani (860 AD), Al-Battani (929 AD) and Ibn Yunus (1000 AD) developed the altitudes, latitudes and the galaxies, which were later, accepted as models in Europe.
Al-Khwarizmi, along with some of his colleagues, developed an astronomical counting table by which the distance and width of earth could be surveyed. This means he took the earth to be round. In 1226 AD, Adelard of Bath translated his theory and the table into Latin and it later became the foundation of all astronomical studies and researches. Al-Khwarizmi's astronomical findings and theories were accepted in Greece, India and even in China.
But above all, Al-Khwarizmi's original contribution was made in algebra of which the Muslims are the fathers. The name Algebra has been derived from his book Hisab al-Jabr. The great historian, Ibn Khaldun, has also testified to this fact. It was from al-Khwarizmi that the Latin and European historians introduced the word, "algarism? and ?algarithm? to express their derivations. The Latin word cipher meaning zero is from the Arabic word, sifr, which was also introduced by the Muslims. And Al-Khwarizmi, the mathematician, was most probably the inventor of zero. The mathematicians of the world know this and acknowledge their debt to him.