1021
Ibn al-Haytham writes the Book of Optics
In Cairo, under house arrest for failing to dam the Nile, the Basra-born scientist completed a seven-volume treatise arguing that vision happened when light…
West Baray reservoir begun at Angkor
Suryavarman I ordered the construction of an immense artificial reservoir eight kilometers long and two kilometers wide at the Khmer capital…
Druze faith emerges from al-Hakim's disappearance
After the Fatimid caliph vanished into the Muqattam hills and never returned, a group of his followers declared him divine and in occultation rather than dead.
Disappearance of Caliph al-Hakim
The erratic Fatimid ruler, who had persecuted Christians and Jews, banned chess, and fasted until he hallucinated, rode out of Cairo one night…
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Frequently asked
What happened in the year 1021?
Saeculum lists 4 events from 1021. The most significant is Ibn al-Haytham writes the Book of Optics.
What era was 1021 part of?
1021 falls within the High Middle Ages (1000-1300). Crusades, cathedrals, and the slow waking of Europe.
Which regions saw notable events in 1021?
The events from 1021 span Middle East and Southeast Asia.