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Ptolemy's world map

Ptolemy's world map is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Ptolemy's world map rather than just read about it. In short: The Ptolemy world map is a map of the world known to Greco-Roman societies in the 2nd century. It is based on the description contained in Ptolemy's book Geography, written c. 150.

Ptolemy's world map — main illustration
Ptolemy's world map — illustration

Key takeaways

  • Ptolemy's world map belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Ptolemy's world map to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Ptolemy's world map from memory before moving on to harder problems.

Reference excerpt

The Ptolemy world map is a map of the world known to Greco-Roman societies in the 2nd century. It is based on the description contained in Ptolemy's book Geography, written c. 150. Based on an inscription in several of the earliest surviving manuscripts, it is traditionally credited to Agathodaemon of Alexandria. Notable features of Ptolemy's map are the first use of longitudinal and latitudinal lines as well as specifying terrestrial locations by celestial observations. The Geography was translated from Greek into Arabic in the 9th century and played a role in the work of al-Khwārizmī before lapsing into obscurity. The idea of a global coordinate system revolutionized European geographical thought, however, and inspired more mathematical treatment of cartography. Ptolemy's work probably originally came with maps, but none have been discovered. Instead, the present form of the map was reconstructed from Ptolemy's coordinates by Byzantine monks under the direction of Maximus Planudes shortly after 1295. It probably was not that of the original text, as it uses the less favored of the two alternate projections offered by Ptolemy.

Continents The continents are given as Europe, Asia, and Libya (Africa). The World Ocean is only seen to the west. The map distinguishes two large enclosed seas: the Mediterranean and the Indian (Indicum Pelagus). Due to Marinus and Ptolemy's mistaken measure of the circumference of the earth, the former is made to extend much too far in terms of degrees of arc; due to their reliance on Hipparchus, they mistakenly enclose the latter with an eastern and southern shore of unknown lands, which prevents the map from identifying the western coast of the World Ocean. India is bound by the Indus and Ganges rivers, but its peninsula is much shortened. Instead, Sri Lanka (Taprobane) is greatly enlarged. The Malay Peninsula is given as the Golden Chersonese instead of the earlier "Golden Island", which derived from Indian accounts of the mines on Sumatra. Beyond the Golden Chersonese, the Great Gulf (Magnus Sinus) forms a combination of the Gulf of Thailand and South China Sea which is bound by the unknown lands thought to enclose the Indian Sea. China is divided into two realms—the Qin (Sinae) and the Land of Silk (Serica)—owing to the different accounts received from the overland and maritime Silk Roads. The Geography and the map derived from it probably played an important role in the expansion of the Roman Empire to the East. Trade throughout the Indian Ocean was extensive from the 2nd century, and many Roman trading ports have been identified in India. From these ports, Roman embassies to China are recorded in Chinese historical sources from around 166. The Danish historian Gudmund Schütte attempted to reconstruct the Danish part of Ptolemy's world map. It includes several place- and tribe-names, some of which Schütte assigned a contemporary equivalent. The most prominent feature of the map is the peninsula Jutland placed north of the river Albis Trêva, west of the Saxonôn Nesôi (archipelago), east of the Skandiai Nêsoi, which itself lies west of a larger island Skandia. Skandia is home to the Goutai in the center, and the Phiraisoi in the east. North of Jutland lies a third archipelago Alokiai Nêsoi. South of the Albis live the Lakkobardoi and to its north the Saxones. The west coast of Jutland is home to the Sigulônes, the Sabaliggio, the Kobandoi, the Eundusioi and the northernmost Kimbroi (possibly Cimbri). North and east is home to the Kimbrikê (possibly Cimbri), the Chersonêsos and the Charudes.

References

External links

Nicholas the German's c. 1480 Florentine edition, the first to use Ptolemy's 2nd projection, at the University of Minnesota Late Ptolemaic maps at Columbia University Richard Donohue's presentation of Ptolemy's projection with modern geographic knowledge D. Gusev, S. Stafeyev GIS Analysis and Digital Reconstruction of Ptolemy's India beyond the Ganges, Serike and Sinae D. Gusev, S. Stafeyev Iterative Reconstruction of Ptolemy’s West Africa Using Modern GIS Analysis D. Gusev, S. Stafeyev Visualization and GIS Analysis of Ptolemy’s One-Sided Globe in the Old and Modern Contexts D. Gusev, S. Stafeyev Claudius Ptolemy’s East Africa Georeferenced and Visualized e-Perimetron, Vol. 18, No 4, 2023 D. Gusev, S. Stafeyev New Digital Reconstruction of Ptolemy’s Iran, Afghanistan, Turkmenistan, and Balochistan D. Gusev, S. Stafeyev Revised Digital Reconstruction of Ptolemy’s India, Taprobane, Serike, and Sinae with map http://history-maps.ru/pictures/all_1/small_2370/

Illustrations

Ptolemy's world map: Ptolemy's world map, reconstituted from Ptolemy's Geography (circa 150) in the 15th century, indicating "Sinae" (China) at the extreme right, beyond the island of "Taprobane" (Ceylon or Sri Lanka, oversized) and the "Aurea Chersonesus" (Southeast Asian peninsula)
Ptolemy's world map, reconstituted from Ptolemy's Geography (circa 150) in the 15th century, indicating "Sinae" (China) at the extreme right, beyond the island of "Taprobane" (Ceylon or Sri Lanka, oversized) and the "Aurea Chersonesus" (Southeast Asian peninsula)
Ptolemy's world map: Detail of East and Southeast Asia in Ptolemy's world map. Gulf of the Ganges (Bay of Bengal) left, Southeast Asian peninsula in the center, South China Sea right, with "Sinae" (China)
Detail of East and Southeast Asia in Ptolemy's world map. Gulf of the Ganges (Bay of Bengal) left, Southeast Asian peninsula in the center, South China Sea right, with "Sinae" (China)

Worked examples

Example 1 — a first encounter with Ptolemy's world map

Start with the simplest possible case. Write down what Ptolemy's world map claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Ptolemy's world map before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Ptolemy's world map ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Ptolemy's world map

In research
Ptolemy's world map appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Ptolemy's world map in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Ptolemy's world map is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2nd-century works, Foreign relations of ancient Rome, Historic maps of the world, so understanding it makes those chapters shorter.
In everyday life
Look for Ptolemy's world map outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Ptolemy's world map in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Ptolemy's world map means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Ptolemy's world map out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ptolemy's world map in simple terms?

The Ptolemy world map is a map of the world known to Greco-Roman societies in the 2nd century. It is based on the description contained in Ptolemy's book Geography, written c. 150.

Why does Ptolemy's world map matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Ptolemy's world map?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Ptolemy's world map.

Tags

  • 2nd-century works
  • Foreign relations of ancient Rome
  • Historic maps of the world
  • Ptolemy

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