What years were in the 12th century?

Answer 1

800-899 AD, methinks. It is probably mostly recognized that the 9th century runs from 800-899.

However, since there was no Year 0, the second century did not rightfully start until the year 101.

So the 9th century is technically comprised of the years 801-900. Just as the 21st century did not technically start until 2001.

Answer 2

1001-1100. Are you thick ?

Answer 3

1101-1200