20 BC

20 BC in various calendars
Gregorian calendar	20 BC; XX BC
Ab urbe condita	734
Ancient Greek era	190th Olympiad (victor)¹
Assyrian calendar	4731
Balinese saka calendar	N/A
Bengali calendar	−612
Berber calendar	931
Buddhist calendar	525
Burmese calendar	−657
Byzantine calendar	5489–5490
Chinese calendar	庚子年 (Metal Rat); 2678 or 2471; — to —; 辛丑年 (Metal Ox); 2679 or 2472
Coptic calendar	−303 – −302
Discordian calendar	1147
Ethiopian calendar	−27 – −26
Hebrew calendar	3741–3742
Hindu calendars
- Vikram Samvat	37–38
- Shaka Samvat	N/A
- Kali Yuga	3081–3082
Holocene calendar	9981
Iranian calendar	641 BP – 640 BP
Islamic calendar	661 BH – 660 BH
Javanese calendar	N/A
Julian calendar	20 BC; XX BC
Korean calendar	2314
Minguo calendar	1931 before ROC; 民前1931年
Nanakshahi calendar	−1487
Seleucid era	292/293 AG
Thai solar calendar	523–524
Tibetan calendar	阳金鼠年; (male Iron-Rat); 107 or −274 or −1046; — to —; 阴金牛年; (female Iron-Ox); 108 or −273 or −1045

Millennium:	1st millennium BC
Centuries:	2nd century BC; 1st century BC ; 1st century;
Decades:	40s BC; 30s BC; 20s BC ; 10s BC; 0s BC;
Years:	23 BC; 22 BC; 21 BC; 20 BC ; 19 BC; 18 BC; 17 BC;

Year 20 BC was either a common year starting on Wednesday or Thursday or a leap year starting on Tuesday, Wednesday or Thursday (link will display the full calendar) of the Julian calendar (the sources differ, see leap year error for further information) and a common year starting on Tuesday of the Proleptic Julian calendar. At the time, it was also known as the Year of the Consulship of Appuleius and Nerva (or, less frequently, year 734 Ab urbe condita). The denomination 20 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

Events

May 12 – Emperor Augustus Caesar negotiates a peace with Parthia, making Armenia a buffer zone between the two major powers. The captured eagles of Marcus Licinius Crassus and Mark Antony are returned.
Based on the scenes and the style of the work, the Portland Vase is believed to have been made in Alexandria some time between this year and AD 100.
King Herod the Great begins renovation of the Temple in Jerusalem.
Maison Carrée, Nîmes, France, is built (approximate date).

The Shakas, a nomadic Iranian tribe, no longer control northwest India (approximate date).

Marcus Verrius Flaccus' De verborum significatu is published. It is one of the first great dictionaries in history.