"Cloud lies to the north of the river and dream to the south. The ancient Yunmeng reaches as far as Qi Zhou on the east, Zhi River on the west, Jing Mountain on the north, and Qingcao on the south"—such was the description of the Great Lake of Yunmen of the Pre-Qin Period.
In its heyday, the great lake was as vast as 26 000 km^2. The sediment deposition in the later years gradually divided Yunmeng Lake into two parts. The part to the north of the Yangtze River became a swamp; a vast lake remained in the part to the south of the Yangtze River, which was Dongting Lake.
Dongting Lake used to cover an area as large as nearly 6000 km^2 in ancient times. However, because of the continuous infiltration of large quantities of sediment and the unbridled modern activities such as lake reclamation and dam-building, it finally shrank to an area of 2623 km^2.
