The population was dense in the 6th century, but it diminished in the 7th and 8th centuries. Epidemics (such as the plague of 541/542 and its recurrences until 747) seem to have had greater effects on population volume than wars. From the 9th century on, the population of the empire increased, but it was unevenly distributed. A growing population would imply an increase in the area under cultivation. The automatic effect of a larger population was also amplified by the demand from a growing number of people who did not produce much or at all. Indeed, it is estimated that areas under cultivation must have almost doubled, and that the extension of crops might have affected a shift in the location of grazing lands, and pushed back the woodlands.