|Centuries:||1st century – 2nd century – 3rd century|
|Decades:||140s 150s 160s – 170s – 180s 190s 200s|
|Years:||175 176 177 – 178 – 179 180 181|
|178 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||931|
|Chinese calendar||丁巳年 (Fire Snake)
2874 or 2814
— to —
戊午年 (Earth Horse)
2875 or 2815
|Coptic calendar||−106 – −105|
|- Vikram Samvat||234–235|
|- Shaka Samvat||100–101|
|- Kali Yuga||3279–3280|
|Iranian calendar||444 BP – 443 BP|
|Islamic calendar||458 BH – 457 BH|
|Minguo calendar||1734 before ROC
|Seleucid era||489/490 AG|
|Thai solar calendar||720–721|
Year 178 (CLXXVIII) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Scipio and Rufus (or, less frequently, year 931 Ab urbe condita). The denomination 178 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.
- Bruttia Crispina marries Commodus and receive the title of Augusta.
- Emperor Marcus Aurelius and his son Commodus arrive at Carnuntum in Pannonia, and travel to the Danube to fight against the Marcomanni.
- Last (7th) year of Xiping era and start of Guanghe era of the Chinese Han Dynasty.
- In India, the decline of the Kushan Empire begins. The Sassanides take over Central Asia.
- Marcus Clodius Pupienus Maximus, later Roman Emperor (approximate date) (d. 238)
- Lu Meng, general of Wu (d. 219)
- Pang Tong, adviser of Liu Bei (d. 214)
- Zhang Cheng, general of Wu (d. 244)