Strictly speaking, Ptolemy was not Greek. He was born in Egypt and was active in Alexandria (now Alexandria, Egypt). We say Ptolemy is a Greek mathematician, astronomer and geographer today. It is because there are two periods of ancient Greek culture: the narrow Greek civilization and the pan-Hellenistic period, which can probably be bounded by Aristotle's death. In a narrow sense, the period of Greek civilization refers to "Athens-Sparta". Ptolemy created many works in his life, among which "Astronomical Masterpiece" is an encyclopedia based on the study of hipparchus. The main content of this book expounds the geocentric system, which holds that the earth is the center and the sun, moon and other stars all revolve around the earth. Another work, Geography Guide, is a summary of geographical knowledge, which was written with reference to the information of Alexandria Library.

Ptolemy thought that geography was of great significance to the whole earth, and he used some place names and measures instead of geographical descriptions. In his Geographic Guide, he connected imaginary inhabited places into a land mass with some basins in the middle, and showed an undiscovered continent south of the Indian Ocean on the map. It was not until the eighteenth century that this mistake was eliminated.

It is speculated that Sai Weng may be his teacher, but this has not been confirmed. Ptolemy entrusted Ju Lushi with many functions. Some people think that Marius is Ptolemy's teacher because he mentioned Marius's information many times in geography class. The above general information is a brief introduction of Ptolemy.