Eratosthenes computes circumference of the Earth — introduced 250 BCE
Eratosthenes computes circumference of the Earth arrived in 250 BCE, during the Ancient World (3rd century BCE). It expanded what people could build, measure, or communicate, and quickly reshaped daily life.
Context
Ancient World — Empires, philosophers, and the first great cities. That's around 2220 years ago — deep history, roughly 22 centuries in the past. Around the same time, the world was also seeing Archimedes' screw (250 BCE) and Great Pyramid of Cholula (Mexico) (250 BCE).
Why it matters
Eratosthenes computes circumference of the Earth mattered because it changed what was possible. New tools shift habits, industries, and even how people see the world — and this one is remembered for exactly that reason.
Did you know?
Just 0 years after, Archimedes' screw (250 BCE) was also making headlines — a reminder how much history can compress into a single decade.
Era
Ancient World
Empires, philosophers, and the first great cities.
Category
Inventions
Inventions are the tools and technologies that changed what humans could do — from wheels and printing presses to satellites and smartphones.
Contemporary events
What else was happening in the world around this time.
Sources & further reading7 verified references · tap to open
About this lesson. Overview, context, and “Why it matters” are generated summaries written for study and gameplay. Dates and category placement come from the Timeline question bank[1]; era descriptions are adapted from standard historical periodisation[2]. For primary sources and in-depth reading, use the references below.
- Timeline question bank — © the game's original author, used with permission.
- Era framework based on Wikipedia's Human history overview, CC BY-SA 4.0.
Wikipedia
Community-maintained encyclopedia entry with citations.
Encyclopædia Britannica
Editorially reviewed reference articles.
Library of Congress
Primary sources, photographs, and archival records.
National Archives
Original U.S. government documents and records.
Smithsonian
Museum collections and curator-written explainers.
BBC History
Long-form explainers and documentaries.
History.com
Timelines and topic overviews from HISTORY.
Educational content notice
Lessons are for general historical education, not professional advice. Some entries touch on wars, violence, or other sensitive events — appropriate for ages 9+. External links open in your browser and are not controlled by Timeline.
Quick check
Which of these happened in 250 BCE?
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