1090

1090 (MXC) was a common year starting on Tuesday of the Julian calendar, the 1090th year of the Common Era (CE) and Anno Domini (AD) designations, the 90th year of the 2nd millennium, the 90th year of the 11th century, and the 1st year of the 1090s decade. As of the start of 1090, the Gregorian calendar was 6 days ahead of the Julian calendar, which was the dominant calendar of the time.

Millennium:	2nd millennium
Centuries:	10th century – 11th century – 12th century
Decades:	1060s  1070s  1080s  – 1090s –  1100s  1110s  1120s
Years:	1087 1088 1089 – 1090 – 1091 1092 1093

Hassan-i Sabbah (c. 1050–1124)

Africa

• Béjaïa becomes the capital of the Hammadid Dynasty in Algeria.

Europe

• Third expedition of the Almoravid army in al-Andalus who subdue the taifas kingdoms. Córdoba, Seville, Grenada, Málaga, Almería and Ronda fall to the troops of Yusuf ibn Tashfin.

Arts and culture

• Troubadours begin playing in Provence.

Technology

• Song Dynasty Chinese writer Qin Guan writes the Can Shu (Book of Sericulture), which describes a silk-reeling machine that has the world's oldest known mechanical belt drive.

Births

• Saint Bernard of Clairvaux (d. 1153)
• Eliezer ben Nathan of Mainz
• Qin Hui, Chinese Song Dynasty Prime Minister (d. 1155)

Deaths

• June 26 – Jaromír (Bishop of Prague)
• July 3 – Egbert II, Margrave of Meissen (b. c. 1060)
• October 6 – Saint Adalbero