Abu Sa'id Ahmed ibn Mohammed ibn Abd al-Jalil al-Sijzi (short for al-Sijistani) was a Persian astronomer and mathematician of Pashtun origin from Sistan. Sijistan or Sistan's a region in the east of current Iran. Its historical name's Sakastan from the name Saka who were East Iranian inhabitants of the region. Sakastan's mentioned in abundance in the Shahnama. Zi or zai means "son of" in Pashto. Sijzi or Sagzi was also the last name of Rustam. Al-Sijzi's thought to have been born around 945 CE,… (More on Al-sijzi)