Who Was When
Who Was When (同时代 in Chinese) answers one question: "I'm looking at this. What else was happening in
the world at the same time?" You type a civilisation, dynasty, war or year, or
photograph a museum label, and it shows what other cultures were alive at that
moment. It is built for travellers and museum visitors on a phone, often on weak
signal, and works in English, Spanish and Simplified Chinese.
Live site: https://whowaswhen.com. It was called Meanwhile until October 2026,
and the repository still is.
What it does
- Cultures and "meanwhile" cards. Each culture page opens with four to six
short cards: what was going on elsewhere in the world while it existed, one
sentence each, with dates.
- World timeline. Every culture as a bar on one chart. Drag the year line
to see who was around in that year.
- Placard scanning. Photograph a museum label in any language and the app
opens the matching culture page, or shows what the label says if there is no
match yet.
- Territory maps. Border maps over time for Rome, Egypt, the Carolingian and
Holy Roman empires, seven Chinese dynasties, the Inca and the Aztecs, and for
two wars before 1800.
- Compare. Two cultures side by side (three on wider screens): how long
they overlapped, with their events on one shared timeline.
- Before and after. Who came before and after a culture in the same place.
- Wars. 39 wars, from the Greco-Persian Wars to the Russo-Ukrainian war,
with dates, sides, events on a map, leaders and attributed death tolls. Six
politically sensitive wars (Korea, Vietnam, the Second Sino-Japanese War, the
Falklands, and two entries for Russia and Ukraine) appear in Spanish or
Chinese only after a person has reviewed that language; until then they are
in English only.
- Country pages. One page per present-day country: the civilisations whose
heartland lies there and the wars fought on its land or by its peoples, on
one timeline.
Languages
English, Spanish (/es/) and Simplified Chinese (/zh/). The interface is
translated in full. Spanish and Chinese data text is machine-translated until
a native speaker reviews it; each culture and war file records which languages
have been reviewed.
No Google services
The site uses no Google fonts, maps, analytics or CDNs, so it loads in
mainland China. Fonts are self-hosted and the Chinese font is cut down to the
characters the site uses. The build fails if a Google host appears anywhere a
browser can receive.
How dates work
Years are stored as astronomical years: 1 CE is 1, 1 BCE is 0, 2 BCE is
-1. The screen never shows a year zero; it shows BCE/CE (or BC/AD, a
setting), and can show "years ago" instead.
Ancient dates are rarely exact. A culture's period has an earliest and latest
possible start and end; the bar is solid where historians agree and fades
across the uncertain edges. Dates and names that historians argue over are
marked disputed, with a note saying why.
Data sources
Every period, event and fact cites at least one source (events at least two),
and facts are written in our own words, never copied from a source. The
credits page lists every source
and what was changed.
| Source | Used for | Licence |
|---|
| PeriodO | Period date ranges | Public domain |
| Wikidata | Names in three languages, identifiers, coordinates | CC0 |
| Pleiades | Ancient place coordinates | CC BY |
| Cliopatria | Historical borders for the territory maps | CC BY 4.0 |
| UCDP | Dates, sides and battle deaths of wars since 1946 | CC BY 4.0 |
| Natural Earth | Coastlines and land under the maps | Public domain |
| Correlates of War | Cross-checking war dates and sides, 1816 to 2014 | Cited only; no data included |
Running it locally
You need Node.js 20.9 or later and pnpm.
pnpm install
pnpm dev # http://127.0.0.1:3000
pnpm build # checks the data, builds, then checks for Google hosts
pnpm start # serves the build
pnpm test
pnpm typecheck
pnpm lint
pnpm validate-data # checks every file in data/ against the schema and rules
Placard scanning sends the photo to Anthropic's Claude API, which reads it;
the photo is not stored or logged. To try it locally, put ANTHROPIC_API_KEY
in .env.local. Without a key everything else works and a scan answers that
scanning is unavailable.
Project layout
CLAUDE.md is the contributor guide: the layout, the data format,
the rules for writing about wars, and the conventions the code follows. The
data lives in data/, one JSON file per culture or war, and
src/lib/data/schema.ts and src/lib/data/war-schema.ts define the fields.
Suggesting a correction
If a date, name or fact is wrong, open an issue with what should change and a
source that supports it (a museum, an academic work or a standard reference).
Corrections without a source can't be checked, so they can't be made.
Licences
