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c. 820 CEReputable source · 2 sourcesWell documented

Al-Khwarizmi Writes the Book That Names Algebra

A scholar in Baghdad's House of Wisdom systematizes equation-solving, and history keeps his name twice over: algebra and algorithm

On the timeline · around c. 820 CE · Medieval and Islamic MathematicsMedieval and Islamic MathematicsAl-Khwarizmi Writes the Book That Names Algebra500 CE600 CE700 CE800 CE900 CE10001100

Quick facts

Al-Khwarizmi's dates
c. 780 CE to c. 850 CE
Treatise title
Hisab al-jabr w'al-muqabala
Word origins
Algebra (from al-jabr); algorithm (from his Latinized name)
Patron
Caliph al-Mamun, Baghdad

What happened

Muhammad ibn Musa al-Khwarizmi, born around 780 CE and dead around 850 CE, worked alongside the Banu Musa brothers as a scholar associated with the House of Wisdom under the patronage of the Caliph al-Mamun in Baghdad. There he wrote a treatise titled Hisab al-jabr w'al-muqabala, the calculation of restoring and balancing, whose two key Arabic operations, al-jabr, moving negative terms to the other side of an equation, and al-muqabala, combining like terms, gave systematic methods for solving linear and quadratic equations. The word algebra comes directly from al-jabr in this title. Al-Khwarizmi also wrote a treatise expounding the Hindu decimal place-value system, which had arrived in the Islamic world from India only recently at that point, and its 12th-century Latin translation, titled Algoritmi de numero Indorum, is the source of the modern word algorithm, a Latinization of his own name.

Why it matters

Al-Khwarizmi's treatise turned equation-solving into an organized discipline with its own name and its own worked methods for the first time, and his separate work on Hindu-Arabic numerals helped move that number system, the one still used everywhere today, from India into the wider Islamic world and eventually into Europe through Latin translation. Two words in everyday modern use, algebra and algorithm, trace directly back to this single scholar's work.

How we know

Al-Khwarizmi's algebra treatise survives in Arabic manuscript and in Frederic Rosen's 19th-century translation, and its content, sources, and the specific patronage of al-Mamun are corroborated across multiple historical treatments of the House of Wisdom period, though modern specialists in Islamic mathematics have revised the popular picture of the House of Wisdom itself, arguing it functioned more as a palace library for translation and copying than as a research academy in the modern sense.

Sources

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Related timelines

  • The Rise of Islam · See the Rise of Islam timeline's entry on al-Khwarizmi and the House of Wisdom for the wider Abbasid translation movement and Baghdad's role as the intellectual capital of the medieval world.
Part of a timelineHistory of Mathematics26 events · A number system built for taxes, a theorem older than the man it's named for, a proof too long for a margin, and an infinity too big to countView all →
Al-Khwarizmi Writes the Book That Names Algebra · History of Mathematics · SourcedStory