AD 999

999 in various calendars
Gregorian calendar	999; CMXCIX
Ab urbe condita	1752
Armenian calendar	448; ԹՎ ՆԽԸ
Assyrian calendar	5749
Balinese saka calendar	920–921
Bengali calendar	406
Berber calendar	1949
Buddhist calendar	1543
Burmese calendar	361
Byzantine calendar	6507–6508
Chinese calendar	戊戌年 (Earth Dog); 3696 or 3489; — to —; 己亥年 (Earth Pig); 3697 or 3490
Coptic calendar	715–716
Discordian calendar	2165
Ethiopian calendar	991–992
Hebrew calendar	4759–4760
Hindu calendars
- Vikram Samvat	1055–1056
- Shaka Samvat	920–921
- Kali Yuga	4099–4100
Holocene calendar	10999
Iranian calendar	377–378
Islamic calendar	389–390
Japanese calendar	Chōtoku 5 / Chōhō 1; (長保元年)
Javanese calendar	900–901
Julian calendar	999; CMXCIX
Korean calendar	3332
Minguo calendar	913 before ROC; 民前913年
Nanakshahi calendar	−469
Seleucid era	1310/1311 AG
Thai solar calendar	1541–1542
Tibetan calendar	阳土狗年; (male Earth-Dog); 1125 or 744 or −28; — to —; 阴土猪年; (female Earth-Pig); 1126 or 745 or −27

Millennium:	1st millennium
Centuries:	9th century; 10th century ; 11th century;
Decades:	970s; 980s; 990s ; 1000s; 1010s;
Years:	996; 997; 998; 999 ; 1000; 1001; 1002;

Year 999 (CMXCIX) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar.

Events

9 February: The Mogi Ceremony of Fujiwara no Shoshi is held (she later becomes empress).
December: Empress Teishi gives birth to Prince Atsuyasu (who becomes the imperial heir), but on the next day, her rival, Fujiwara no Shoshi, is promoted to Consort.

King Bermudo II abdicates in favor of his 5-year-old son Alfonso V as ruler of León. Moorish invaders have forced Bermudo to recognize the suzerainty of their leader, Umayyad vizier and the de facto ruler Al-Mansur.
9 September (999 or 1000) – Battle of Svolder: A Norwegian fleet, commanded by Olaf Tryggvason, is defeated by the combined fleet of the Danish king Sweyn Forkbeard and his Swedish counterpart Olaf the Swede, resulting in Tryggvason's death, and the splitting up of Norway between Sweden and Denmark.

The Karakhanids invade from north of the Syr Darya River, ending the Samanid Empire (modern Iran). The Samanid domains are split between the Ghaznavid Dynasty and the Karakhanids.

February 18 – Pope Gregory V dies after a 3-year pontificate in which the Crescentii family forced him to flee Rome. He is succeeded by Sylvester II as the 139th pope of the Catholic Church.
Bishop Aldhun consecrates a cathedral (later Durham Cathedral), at a site where the remains of St. Cuthbert had been moved to in AD 995 from Lindisfarne because of the danger of Viking raids.
Sigmundur Brestisson, a Viking chieftain, introduces Christianity in the Faroe Islands.