Studying the ancient Iranian literature, We can find out, that, our ancestors believed in sphericity of the earth. It can be understood from their indirect remarks, when they were describing the movements of the stars, Zodiac, Seasonal changes, etc. In post-Islamic ages, Persian scientists took further steps to prove the hypothesis of sphericity of earth. * Abu Rayhan Biruni (973—l048 A.D.) accomplished some valuable research and compared his methods, measurements and achievements with the previous literature. He wrote some chapters on how to determine the latitude of different locations, distance between cities and other Sidereal, and terrestrial measurements. Ancient geographers divided the inhabited World into several geographical regions or climates, by two methods; first by using the circles parallel to the equator. They believed that only northern hemisphere is inhabited and the southern one is empty of life. Based on this belief, they drew some parallel lines to the equator and divided the northern hemisphere into seven climates. Second classification was based on a central climate. Biruni believes that division based on the parallel lines to the equator comes from Greece and, Iranians divided the inhabited World into seven climates as following: First, Climate: India and Indus and their islands. Second climate: Hejaz, Ethiopia, Aden, Yemen, and Bahrain. Climate three: Egypt, Levant, and Morocco. Climate four: Babylon, Iraq, Fars, Khorasan, Sistan, Zabulistan and Tokharestan. Fifth climate: Rome, Andalusia, Europe, Azerbaijan and Darband. Sixth climate: Ya’juj, Časpian Sea, Ghazni, Kyrgyzstan, Kimak, Russia and Slavs, and the seventh climate: China, Tibet, Hotan, Balkh and TransOxiana. Mohammad ibn Musa Khwarizmi, formerly Latinizedi as Algoritmi,(780—850 A.D.) Was a Persian scientist and geographer and one of the first, Scholars Who di Schussed the climates based on the latitude. Al-Mas’udi (896-956 A.D.) was a Muslim historian and geographer who attributed not only the planets but also the Zodiac to the seven climes.