1258Centuries: 12th century - 13th century - 14th century
- February 10 - Mongols overrun Baghdad, burning it to the ground and killing 10,000 citizens
- Llywelyn the Last declares himself Prince of Wales. He is the final ruler of an independent Wales, before its conquest by the English.
- John IV Lascaris succeeds his father Theodore II Lascaris as emperor of Nicaea. Due to his young age, he is appointed as regent Michael VIII Palaeologus.