A museum of human timekeeping

Calendar Timeline

Follow how civilizations moved from lunar observation and agricultural seasons to civic reforms, religious calendars, international standards and machine time.

Calendar history timeline calendar illustration

Ancient

Ancient Egyptian Civil Calendar

At least Old Kingdom era · Ancient Egypt

Babylonian Calendar

Ancient Mesopotamian tradition · Mesopotamia

Assyrian Calendar Traditions

Ancient · Ancient Assyria / Mesopotamia

Attic Calendar

Classical antiquity · Ancient Athens

Ancient Hebrew Observational Calendar

Ancient · Ancient Israel

Roman Republican Calendar

Before Julian reform · Roman Republic

Maya Tzolkʼin

Pre-Columbian · Mesoamerica

Maya Haabʼ

Pre-Columbian · Mesoamerica

Maya Long Count

Pre-Columbian · Mesoamerica

Aztec Tonalpohualli

Pre-Columbian · Central Mexico

Aztec Xiuhpohualli

Pre-Columbian · Central Mexico

Classical

Julian Calendar

45 BCE reform · Roman world; later Europe and Christian traditions

Late Antique to Modern

Coptic Calendar

Alexandrian / ancient Egyptian lineage · Coptic Christian communities

Ethiopian Calendar

Alexandrian tradition · Ethiopia

Medieval

Armenian Calendar

Traditional Armenian era · Historic Armenia

Byzantine Calendar

Late antiquity / medieval · Byzantine Empire and Orthodox world

Jalali Calendar

11th century · Persian world

Medieval to Modern

Islamic / Hijri Calendar

Hijra era beginning 622 CE · Muslim communities worldwide

Tabular Islamic / Civil Calendar

Traditional arithmetic form · Computational use

Malayalam / Kollam Era Calendar

Kollam Era, 9th century CE · Kerala

Tibetan Calendar

Traditional Tibetan astronomical systems · Tibetan cultural regions

Ancient to Modern

Traditional Chinese Calendar

Ancient; documented by Shang-era evidence · China and Chinese communities worldwide

Chinese Sexagenary Cycle

Ancient · East Asia

Hebrew / Jewish Calendar

Ancient roots; later fixed calculated form · Jewish communities worldwide

Zoroastrian Calendars

Ancient Iranian traditions · Iranian and Parsi communities

Hindu Panchanga Calendars

Ancient Indian astronomical traditions · India, Nepal, Bali and Hindu communities worldwide

Early Modern to Modern

Bengali Calendar

Historical Bengali era with later reforms · Bangladesh and eastern South Asia

Javanese Calendar

17th-century reform combining older Javanese and Islamic elements · Java, Indonesia

Rumi / Ottoman Fiscal Calendar

Ottoman administrative reforms · Ottoman Empire

Early Modern / Revolutionary

French Republican Calendar

1793 official adoption · Revolutionary France

Modern Historical

Soviet Revolutionary Work Calendars

Late 1920s–1940 · Soviet Union

Modern

Umm al-Qura Calendar

Modern official computational system · Saudi Arabia

Indian National / Saka Calendar

National reform adopted 1957 · India

Thai Solar / Buddhist Era Calendar

Modern civil form · Thailand

Japanese Era Calendar

Modern era system layered on Gregorian calendar · Japan

Minguo / Republic of China Calendar

Era beginning 1912 · Taiwan

Baháʼí / Badíʿ Calendar

1844 era · Baháʼí communities worldwide

Nanakshahi Calendar

Modern standardized Sikh calendar · Sikh communities

Gregorian Calendar

1582 reform · Worldwide

Revised Julian Calendar

20th century · Some Eastern Orthodox churches

Modern civil use

Nepal Bikram Sambat

Traditional era; modern official use · Nepal

Modern Technical

ISO 8601 Week-Date

International standard · Worldwide

Modern Scientific

Julian Day / Julian Date

Chronological system introduced in early modern astronomy · Astronomy worldwide

Modified Julian Date

Modern technical convention · Astronomy / geodesy / technical systems

GPS Time

Epoch 1980-01-06 · Global navigation systems

Modern Computing

Unix Time

Epoch 1970-01-01 UTC · Computing worldwide

Modern Proposed

International Fixed Calendar

19th–20th century reform movement · International proposal

World Calendar

20th century calendar reform · International proposal

Positivist Calendar

Auguste Comte, 19th century · 19th-century intellectual history

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