List of state leaders in 857

856 state leaders - Events of 857 - 858 state leaders - State leaders by year

---

Asia

• Bohai/Balhae -
  1. Da Yizhen/Dae I-jin, King of Bohai/Balhae (830-857)
  2. Da Qianhuang/Dae Geon-hwang, King of Bohai/Balhae (857-871)
• China (Tang Dynasty) - Xuanzong, Emperor of Tang China (846-859)
• Gurjara - Mihira Bhoja I, Pratihara King of Gurjara (c. 836-886)
• Japan (Heian Period) - Emperor Montoku, emperor of Japan (850-858)
• Silla -
  1. Munseong, King of Silla (839-857)
  2. Heonan, King of Silla (857-861)

Europe

• East Anglia¹ - Edmund, King of East Anglia (855–870)
• England - Æthelbald of Wessex, Bretwalda (856–860)
• Friesland - Rorik, King of the Danish Vikings in Friesland (850-880)
• Mercia - Burgred, King of Mercia (852–874)
• Northumbria¹ - Osbert, King of Northumbria (849–867)
• Ireland -
  • Bard of Limerick, High King of Ireland (845–880)
  • Mael Seachlainn I, High King of Ireland (845–860)
• Scotland - Kenneth I, King of Scots and Picts (843–858)
• Strathclyde - Arthgal f Dyfnwal, King of Strathclyde (816–872)
• Wales - Rhodri Mawr ap Merfyn, King of Gwynedd (844–878)

Notes

1. Though East Anglia, Northumbria and Mercia are traditionally perceived to have been in the heptarchy they were largely independent kingdoms until its conquest by the Danes in 869 and 867, respectively - where Mercia was conquered by Wessex in 874. All other members of the heptarchy had been conquered by Wessex and by this time had no form or king.