Al-Khwarizmi
c. 780 CE–c. 850 CE · Kath (Khwarazm)
Muhammad ibn Musa al-Khwarizmi (c. 780 – c. 850 CE) was a mathematician, astronomer, and geographer who worked in Abbasid Baghdad. His birth and death dates are traditional estimates rather than firmly recorded. His name (nisba) points to Khwarazm, a region south of the Aral Sea in Greater Iran (today split between Uzbekistan and Turkmenistan), and the bibliographer Ibn al-Nadim names Khwarazm as his origin. The historian al-Tabari, however, attaches the epithet "al-Qutrubbulli," pointing to Qutrubbul near Baghdad; some scholars (e.g. David King) read him as born just outside Baghdad, while Roshdi Rashed argues al-Tabari's text was garbled and conflates two people. The site treats his birthplace as genuinely disputed.
What is well attested is his activity, around 820 CE, at the House of Wisdom (Bayt al-Hikma), a center of scholarship and translation in Baghdad associated with the caliph al-Ma'mun, to whom al-Khwarizmi dedicated works. His Arabic treatise on "al-jabr wa'l-muqabala" (roughly, restoration and balancing) set out systematic methods for solving linear and quadratic equations; the short title al-jabr became the European word "algebra." A separate work explaining Hindu-Arabic numerals reached Latin readers as "Algoritmi de numero Indorum," and his Latinized name "Algoritmi" is the root of "algorithm." He also compiled astronomical tables (the Zij al-Sindhind) and a geography, Kitab Surat al-Ard, revising Ptolemy's coordinates. Details of his religious life are not securely documented.
Did you know?
Two everyday math words are one man's name and his book title
Around 820 CE the Baghdad scholar al-Khwarizmi wrote a treatise whose Arabic title contained the word "al-jabr" — the root of our word "algebra." When his works were later rendered into Latin, his own name was Latinized as "Algoritmi," which is where the word "algorithm" comes from. Both terms are still in daily use roughly 1,200 years later.
How we know
al-Khwarizmi (c. 780 – c. 850 CE); Al-Jabr (al-Kitāb al-mukhtaṣar fī ḥisāb al-jabr wa'l-muqābala) written c. 820 CE at Baghdad's House of Wisdom; "algebra" from "al-jabr" (Robert of Chester's 1145 Latin translation), "algorithm" from his Latinized name "Algoritmi."
A mathematician in Baghdad while Charlemagne ruled Europe
Al-Khwarizmi — the Baghdad mathematician whose Latinized name gave English the word “algorithm” — was born around 780, while Charlemagne was building his empire across Europe (he was crowned emperor in 800). The Hindu-Arabic calculating methods al-Khwarizmi helped systematize would not take firm hold in Latin Europe until Leonardo of Pisa (Fibonacci) championed them in his Liber Abaci of 1202, nearly four centuries later.
How we know
al-Khwarizmi c.780–850 CE (algebra treatise compiled 813–833, Baghdad House of Wisdom); Charlemagne 748–814, crowned emperor 800; Fibonacci's Liber Abaci 1202. Overlap 780–814 = 34 yrs; 1202 − c.820 = 382 yrs (~4 centuries).
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Kath (Khwarazm)
What they did here
His name al-Khwarizmi points to the region of Khwarazm (south of the Aral Sea), and Ibn al-Nadim names it as his origin; Kath was a principal town of that region. But this rests on the nisba, not on a documented residence, and al-Tabari's epithet 'al-Qutrubbulli' (Qutrubbul, near Baghdad) leads some scholars to place his birth near Baghdad instead; Roshdi Rashed disputes the reading altogether. The Khwarazm link is therefore traditional/uncertain, not attested.
About Kath (Khwarazm)
Kath was the old capital of the region of Khwarazm, on the right bank of the Oxus (Amu Darya) in present-day Uzbekistan, before the seat of power shifted to Gurganj. The polymath al-Biruni (d. c. 1050) was born in or near Kath; the mathematician al-Khwarizmi (9th c.), from whose name 'algorithm' derives, took his nisba from Khwarazm.
The world in their lifetime
Thinkers and teachers of other traditions whose lives overlapped with Al-Khwarizmi’s — a glimpse of the wider world they lived in. Drawn purely from recorded birth and death years.
Works
No works attributed in the corpus yet.