Double Ditch Indian Village, overlooking the Missouri River, was a large earthlodge village inhabited by Mandan Indians between AD 1490 and 1785. The remains of earthlodges, midden mounds, and two fortification ditches are clearly visible today, and recent investigations revealed two additional fortification systems not evident on the present ground surface. Along the Missouri River in North and South Dakota, Double Ditch is the most spectacular prehistoric earthlodge village that continues to be well preserved. The Mandans were one of the best-known agricultural tribes of the Missouri Valley Region, with a rich and elaborate culture based on farming and bison hunting. According to Mandan oral history, Double Ditch was one of seven to nine villages simultaneously occupied near the mouth of the Heart River, where the Mandan population probably totaled 10,000 or more during this time. Occupied for nearly 300 years, the earthlodge villages were centers of trade between the Mandans, their nomadic neighbors, and later Euroamerican traders. The earliest known direct contact between white traders and the Mandan Indians occurred in December 1738 near present-day Bismarck, and after 1763 trading between Mandans and Euroamerican traders increased. A massive smallpox epidemic swept the interior of North America about 1781-1782 and was apparently responsible for the abandonment of Double Ditch and all other Mandan villages near the Heart River. By the year 1800 the Mandan population was reduced to perhaps 1,200 individuals. In 1804 Lewis and Clark, traveling upriver, observed a band of Teton Dakotas camping near the abandoned village, and Native American people told them that it had been vacant for about twenty-five years, after the Mandans had moved to new villages farther upriver. Descendants of the Mandan people who lived at Double Ditch live today on the Fort Berthold Indian Reservation near New Town.