The 800s decade ran from January 1, 800, to December 31, 809.
The 810s decade ran from January 1, 810, to December 31, 819.
The 820s decade ran from January 1, 820, to December 31, 829.
The 830s decade ran from January 1, 830, to December 31, 839.
The 840s decade ran from January 1, 840, to December 31, 849.
The 850s decade ran from January 1, 850, to December 31, 859.
The 860s decade ran from January 1, 860, to December 31, 869.
The 870s decade ran from January 1, 870, to December 31, 879.
The 880s decade ran from January 1, 880, to December 31, 889.
Year 840 (DCCCXL) was a leap year starting on Thursday in the Julian calendar, the 840th year of the Common Era (CE) and Anno Domini (AD) designations, the 840th year of the 1st millennium, the 40th year of the 9th century, and the 1st year of the 840s decade.
The 900s decade ran from January 1, 900, to December 31, 909.
Year 809 (DCCCIX) was a common year starting on Monday of the Julian calendar, the 809th year of the Common Era (CE) and Anno Domini (AD) designations, the 809th year of the 1st millennium, the 9th year of the 9th century, and the 10th and last year of the 800s decade.
Year 820 (DCCCXX) was a leap year starting on Sunday of the Julian calendar.
Year 862 (DCCCLXII) was a common year starting on Thursday of the Julian calendar.
Year 864 (DCCCLXIV) was a leap year starting on Saturday of the Julian calendar.
Year 846 (DCCCXLVI) was a common year starting on Friday of the Julian calendar.
Year 833 (DCCCXXXIII) was a common year starting on Wednesday of the Julian calendar.
Year 835 (DCCCXXXV) was a common year starting on Friday of the Julian Calendar.
Year 868 (DCCCLXVIII) was a leap year starting on Thursday of the Julian calendar.
Year 905 (CMV) was a common year starting on Tuesday of the Julian calendar.
