1037 (The People's Chronology)
Harold I Harefoot gains recognition as king of England while his rival Hardecanute is detained in Denmark.
Castile's Ferdinand I conquers the Spanish kingdom of León by defeating his brother-in-law Bermudo II and makes himself king (see 1035). León and Castile will remain joined until 1157.
The Constitutio de Feudis issued by the Holy Roman Emperor Conrad II confers hereditary status on the Italian fiefs of small landholders.
The Persian physician-philosopher Avicenna (Ibn Sina) dies at Hamadan at age 57 (approximate).