Decades: 770s 780s 790s 800s 810s - 820s - 830s 840s 850s 860s 870s

Years: 817 818 819 820 821 - 822 - 823 824 825 826 827

• Abd-ar-rahman II becomes ruler of Umayyad Spain.
• Begin of the power struggle between Byzantine Emperor Michael II and Thomas.
• Rabanus Maurus becomes abbott of Fulda.

Deaths

• Tahir ibn Husayn, founder of the Tahirid dynasty