900 AD world map

Border history

The interactive map lets you inspect named territories in 900 AD and compare them to earlier or later snapshots on the timeline.

Biographical context

This page highlights figures close to 900 AD so readers can move from geography to biography without leaving the Historiqly ecosystem.

Era-based reading

The related chronicles below surface long-form reading connected to the medieval period.

Rayy / Baghdad / Persia

Al-Razi

c. 854 – 925

“It grieves me to oppose and criticize the man Galen from whose sea of knowledge I have drawn much.”

First clinical distinction of smallpox from measles, empirical medicine, alchemy, critique of Galen's humoral theory

Egypt & Babylonia

Saadia Gaon

882 CE – 942 CE

“Our nation, the Children of Israel, is a nation only by virtue of its Torah.”

First systematic Jewish philosopher, translator of the Torah into Arabic, Gaon of Sura

Babylonia (modern Iraq)

Hai Gaon

939 CE – 1038 CE

“Observe every custom not in direct opposition to law.”

Gaon of Pumbedita, master of Talmudic law, author of nearly one thousand responsa, last and greatest of the Geonim

Baghdad

Al-Khwarizmi

c. 780 CE – c. 850 CE

“What is easiest and most useful in arithmetic, such as men constantly require in cases of inheritance, legacies, partition, lawsuits, and trade.”

Father of algebra, originator of the word 'algorithm', pioneer of Hindu-Arabic numerals in the Islamic world

Persia / Central Asia

Ibn Sina

c. 980 CE – 1037 CE

“Medicine is the science by which we learn the various states of the human body, in health and when not in health.”

Author of the Canon of Medicine, philosopher of the Islamic Golden Age, synthesiser of Greek and Islamic medical tradition

India (Kerala to the Himalayas)

Shankara

c. 788 CE – c. 820 CE

“Brahma satyam jagat mithyam, jivo brahmaiva naparah.”

Founder of Advaita Vedanta, philosopher of non-dualism, unifier of Hindu thought across India

Rayy / Baghdad / Persia · Scientist

Al-Razi

The Physician Who Doubted Galen

The Persian physician who first distinguished smallpox from measles, distilled alcohol for medicine, wrote the largest medical encyclopedia of the ancient world, and dared to challenge the greatest medical authority in history — in his own words.

Egypt & Babylonia · Philosopher

Saadia Gaon

The Father of Jewish Philosophy

The Egyptian-born scholar who became the most formidable Jewish intellectual of the medieval world — translator of the Torah, author of the first systematic work of Jewish philosophy, and the Gaon who single-handedly stopped the fracturing of the Jewish calendar.

Babylonia (modern Iraq) · Philosopher

Hai Gaon

The Last Light of Babylon

The last and greatest of the Geonim — the scholar who answered questions from Jews across four continents, shaped the foundations of Jewish law for a millennium, and whose death in 1038 ended five centuries of Babylonian Jewish supremacy.

Baghdad · Thinker

Al-Khwarizmi

The Man Who Invented Algebra

The Baghdad scholar who gave the world algebra and the word algorithm — how a ninth-century polymath at the House of Wisdom synthesised Greek, Indian, and Persian mathematics into a system that would power every equation ever written.