For millennia, agriculture has played an important role in the Chinese economy and society. By the time the People's Republic of China was established in 1949, virtually all arable land was under cultivation; irrigation and drainage systems constructed centuries earlier and intensive farming practices already produced relatively high yields. But little prime virgin land was available to support population growth and economic development. However, after a decline in production as a result of the Great Leap Forward (1958–60), agricultural reforms implemented in the 1980s increased yields and promised even greater future production from existing cultivated land.