The Last 2,000 Years When records of drought for the last two millennia are examined, the major 20th century droughts appear to be relatively mild in comparison with other droughts that occurred within this time frame. Even the 16th century drought appears to be fairly modest, when compared to some early periods of drought. Although there are still a few high resolution (offering data on annual to seasonal scales), precisely dated (to the calendar year), tree-ring records available that extend back 2,000 years, most of the paleodrought data that extends back this far are less precisely dated and more coarsely resolved. These records reflect periods of more frequent drought, or drier overall conditions rather than single drought events, so it difficult to compare droughts in these records with 20th century drought events. However, the 20th century can still be evaluated in this context, and we can assess whether parts of the 20th century or the 20th century as a whole were wetter or drier than in the past with these records. The studies below illustrate some paledrought records for the past 2,000 years: Moon Lake Record of Great Plains Drought Rainfall Reconstructions for New Mexico A Multimillennial-length Record of Precipitation from Bristlecone Pine Drought and Mayan Civilization Collapse Back to... The Data.