en 1091

1091 in various calendars
Gregorian calendar	1091; MXCI
Ab urbe condita	1844
Armenian calendar	540; ԹՎ ՇԽ
Assyrian calendar	5841
Balinese saka calendar	1012–1013
Bengali calendar	497–498
Berber calendar	2041
English Regnal year	4 Will. 2 – 5 Will. 2
Buddhist calendar	1635
Burmese calendar	453
Byzantine calendar	6599–6600
Chinese calendar	庚午年 (Metal Horse); 3788 or 3581; — to —; 辛未年 (Metal Goat); 3789 or 3582
Coptic calendar	807–808
Discordian calendar	2257
Ethiopian calendar	1083–1084
Hebrew calendar	4851–4852
Hindu calendars
- Vikram Samvat	1147–1148
- Shaka Samvat	1012–1013
- Kali Yuga	4191–4192
Holocene calendar	11091
Igbo calendar	91–92
Iranian calendar	469–470
Islamic calendar	483–484
Japanese calendar	Kanji 5; (寛治５年)
Javanese calendar	995–996
Julian calendar	1091; MXCI
Korean calendar	3424
Minguo calendar	821 before ROC; 民前821年
Nanakshahi calendar	−377
Seleucid era	1402/1403 AG
Thai solar calendar	1633–1634
Tibetan calendar	阳金马年; (male Iron-Horse); 1217 or 836 or 64; — to —; 阴金羊年; (female Iron-Goat); 1218 or 837 or 65

Millennium:	2nd millennium
Centuries:	10th century; 11th century ; 12th century;
Decades:	1070s; 1080s; 1090s ; 1100s; 1110s;
Years:	1088; 1089; 1090; 1091 ; 1092; 1093; 1094;

Events

Spring – Tzachas, a Seljuk Turkish military commander, establishes an independent maritime state centred in the Ionian coastal city of Smyrna (modern-day İzmir). He proclaims himself emperor (basileus), and concludes an alliance with the Pechenegs in Thrace. Tzachas uses his fleet to blockade Constantinople by sea, while the Pechenegs besiege the capital by land.^[1]
April 29 – Battle of Levounion: Emperor Alexios I, supported by his allies, defeats 80,000 of Pechenegs (including women and children) at the Evros River, near Enos (modern Turkey). The Cumans and Byzantine forces fall upon the enemy camp, slaughtering all in their path. The Pechenegs are butchered so savagely, that this people is almost wiped out.

Spring – King Stephen II, the last member of the Trpimirović dynasty, dies without leaving an heir after a 2-year reign. War and unrest breaks out in Croatia afterwards. King Ladislaus I of Hungary, on instigation of his sister, Queen Helena, intervenes in the conflict and occupies Croatia. He proclaims himself king, but is contested by the Croatian nobleman Petar Snačić.
February – Norman conquest of Sicily: The Normans conquer Noto and complete the 30-year-long conquest of Sicily from the Moorish rulers. Duke Roger Borsa (a son of Robert Guiscard) surrenders his share in the castles of Calabria, and receives his inheritance of Palermo. He grants charters to various towns and encourages urban planning in Apulia and Calabria.
Summer – The Norman invasion of Malta: A Norman fleet led by Count Roger I of Sicily ("Bosso") arrives in Malta. Roger disembarks his army, and besieges the island's capital Medina (modern-day Mdina). The inhabitants negotiate peace terms (by promising to pay an annual tribute) and swear an oath of loyalty to Roger. On the way back, the Normans sack the island Gozo.
July – The Abbadid dynasty ruling in Al-Andalus (modern Spain) falls when Almoravid forces storm Seville. Confronted with this threat, Emir Muhammad ibn Abu Bakr Muhammad al-Aftas of Badajoz obtains the support of King Alfonso VI ("the Brave") of Castile, in exchange for the Moorish positions on the river Tagus (Sintra, Santarém and Lisbon).^[2]

February 2 – King William II of England invades western Normandy with a large army. His brothers, Henry and Robert Curthose, mobilize mercenary forces to resist him during a siege at Mont-Saint-Michel. Under terms of the Treaty of Caen, estates on the Cotentin Peninsula of Normandy are surrendered to William, matters being concluded in August.^[3]
July – King Malcolm III of Scotland invades England, reaching as far south as Durham. The Normans led by William II and Robert march north to oppose the Scots, but a conflict is averted. Malcolm is forced to accept the terms of the Treaty of Abernethy (1072) and pays homage to William.^[3]
Cardiff Castle in Wales is constructed by Robert Fitzhamon, Norman lord of Gloucester (approximate date).

October 17 – London tornado: A T8 tornado (roughly equal to an F4 on the Fujita scale) occurs in London. The wooden London Bridge is demolished and the church of St. Mary-le-Bow is badly damaged.

December – Athanasius VI bar Khamoro becomes (against his will) patriarch and head of the Syriac Orthodox Church in Antioch (until 1129).

March 26 – Wallada bint al-Mustakfi, Andalusian female poet (b. 994)
June 17 – Dirk V, count of Friesland (west of the Vlie) (b. 1052)
June 29 – Frederick of Montbéliard, margrave of Turin
July 5 – William of Hirsau, German abbot and music theorist
August 8 – Altmann of Passau, German bishop and saint
August 25 – Sisnando Davides, Mozarab military leader
December 19
- Adelaide of Susa, margravine of Turin
- Fujiwara no Tadaie, Japanese statesman (b. 1033)
Fu Yaoyu, Chinese government official and politician (b. 1024)
Helena of Hungary, queen consort of Croatia (approximate date)
Jordan I (or Giordano), Italo-Norman prince of Capua
Mac meic Aedh Ua Flaithbheartaigh, Irish king of Iar Connacht
Robert D'Oyly, Norman nobleman (approximate date)
Stephen II (or Stjepan), king of Croatia (approximate date)
Wolfhelm of Brauweiler, German Benedictine abbot
Artuk Bey (Zaheer-ul-Daulah Artuk Beg), Seljuk general and governor

^ Brian Todd Carey (2012). Road to Manzikert: Byzantine and Islamic Warfare (527–1071), p. 160. ISBN 978-1-84884-215-1.
^ Picard, Christophe (2000). Le Portugal musulman (VIIIe-XIIIe siècle. L'Occident d'al-Andalus sous domination islamique. Paris: Maisonneuve & Larose. p. 109. ISBN 2-7068-1398-9.
^ ^a ^b Palmer, Alan; Palmer, Veronica (1992). The Chronology of British History. London: Century Ltd. ISBN 0-7126-5616-2.