Yinsuo Island archaeological site, Archaeological site in Haidong Zhen, China.

Yinsuo Island is a shell mound site on a small island in the southeastern part of Erhai Lake, in Haidong Town, Dali City. It consists of Neolithic to Shang Dynasty deposits, with excavated house foundations and a 600-square-meter area opened in 2003–2004 and 2006. The mound contains shells, pottery, and stone tools.

Wooden stakes found in 1972 during fish-pond construction on Yinsuo Island were carbon-dated to 2600±90 years ago, and a complete double-handled jar held 13 Han wuzhu coins, 61 Wang Mang 'dabu huangqian' coins and 271 'daquan wushi' coins. The site was first identified as a Spring and Autumn to Han period culture. In 2000 the Yunnan Provincial Institute of Cultural Relics and Archaeology and the Dali City Museum found shell-midden traces being destroyed and applied to re-excavate; two campaigns in 2003–2004 and 2006 uncovered 600 square metres, including house foundations. It was named a Dali City protected unit in 1985 and a National Key Cultural Relics Protection Unit in 2013.

Islanders call the shell mounds beiqiu; the excavated shells had their tails broken open, showing they were food waste. The 1972 fish-pond dig also brought up a double-eared jar, about 12 cm high and 15 cm across the mouth, holding 13 Han wuzhu coins, 61 Wang Mang-era dabu huangqian and 271 daquan wushi coins.

The site lies on Yinsuo Island in the southeastern part of Erhai Lake, reached by boat from the Erhai shore near Haidong Town. Excavations in 2003–2004 and 2006 covered 600 square metres and exposed house foundations, so ground surfaces are uneven. A local guide can point out the shell-mound deposits and the excavated areas.

The 1972 fish-pond dig turned up wooden stakes dated by carbon-14 to 2600±90 years ago, plus a complete double-handled jar about 12 cm high and 15 cm across. Inside were 13 Han wuzhu coins, 61 Wang Mang-era dabu huangqian and 271 daquan wushi coins.