Under the Yongle Emperor of Ming China, work begins to reinstate the ancient Grand Canal of China, which fell into disuse and dilapidation during the previous Yuan dynasty. Between 1411 and 1415, a total of 165,000 laborers dredge the canal bed in Shandong, build new channels, embankments, and canal locks. Four large reservoirs in Shandong are also dug, in order to regulate water levels, instead of resorting to pumping water from local tables. A large dam is also constructed, to divert water from the Wen River southwest into the Grand Canal.