Wikipedia wrote:Alexander Grothendieck (German: [ˈɡroːtn̩diːk]; French: [ɡʁɔtɛndik]; 28 March 1928 – 13 November 2014[1]) was a French[2][3][4] mathematician, and a central figure behind the creation of the modern theory of algebraic geometry. His research program vastly extended the scope of the field, incorporating major elements of commutative algebra, homological algebra, sheaf theory, and category theory into its foundations. This new perspective led to revolutionary advances across many areas of pure mathematics.

Born in Germany, Grothendieck was raised and lived primarily in France, although he can be said to have spent much of his working life stateless. He consistently spelt his first name "Alexander" rather than the French "Alexandre";[5] his family name, "Grothendieck" (from his mother) is Low German, which is similar to Dutch, hence he is sometimes mistakenly believed to be of Dutch origin.[6]

After a very productive public mathematical career lasting 1949–1970, particularly 1958–1970 (when he was at IHES), Grothendieck largely ceased mathematical activity after 1970 (age 42), though with some private work 1970–1988. Driven by deep personal and political convictions, Grothendieck left the Institut des Hautes Études Scientifiques, where he had been appointed professor and accomplished his greatest work, after a dispute over military funding in 1970. His mathematical activity essentially ceased after this, and he devoted his energies to political causes, though he did produce some mathematical work privately. He formally retired in 1988 and within a few years moved to the Pyrenees, where he lived in isolation from human society until his death in 2014.

Note that the "Institut des Hautes Études Scientifiques" was practically created for him.

https://en.wikipedia.org/wiki/Alexander_Grothendieck