400

400 (CD) was a leap year starting on Sunday of the Julian calendar, the 400th year of the Common Era (CE) and Anno Domini (AD) designations, the 400th year of the 1st millennium, the 100th and last year of the 4th century, and the 1st year of the 400s decade. As of the start of 400, the Gregorian calendar was 1 day ahead of the Julian calendar, which was the dominant calendar of the time.

Millennium:	1st millennium
Centuries:	3rd century – 4th century – 5th century
Decades:	370s  380s  390s  – 400s –  410s  420s  430s
Years:	397 398 399 – 400 – 401 402 403

400 in other calendars

Gregorian calendar	400 CD
Ab urbe condita	1153
Assyrian calendar	5150
Balinese saka calendar	321–322
Bengali calendar	−193
Berber calendar	1350
Buddhist calendar	944
Burmese calendar	−238
Byzantine calendar	5908–5909
Chinese calendar	己亥年 (Earth Pig) 3096 or 3036     — to — 庚子年 (Metal Rat) 3097 or 3037
Coptic calendar	116–117
Discordian calendar	1566
Ethiopian calendar	392–393
Hebrew calendar	4160–4161
Hindu calendars
- Vikram Samvat	456–457
- Shaka Samvat	321–322
- Kali Yuga	3500–3501
Holocene calendar	10400
Iranian calendar	222 BP – 221 BP
Islamic calendar	229 BH – 228 BH
Javanese calendar	283–284
Julian calendar	400 CD
Korean calendar	2733
Minguo calendar	1512 before ROC 民前1512年
Nanakshahi calendar	−1068
Seleucid era	711/712 AG
Thai solar calendar	942–943
Tibetan calendar	ས་མོ་ཕག་ལོ་ (female Earth-Boar) 526 or 145 or −627     — to — ལྕགས་ཕོ་བྱི་བ་ལོ་ (male Iron-Rat) 527 or 146 or −626

Events

• First invasion of Italy by Alaric (probable date).
• The Vandals start their westward trek from Dacia and Hungary (approximate date).
• Construction (and therefore occupation) at Great Zimbabwe begins (approximate date).
• Earliest date of human occupation on Easter Island (approximate date).
• Chrysanthemums are introduced to Japan (approximate date).