Hazel Wright suggested that word Ouachita owa chito is a Choctaw phrase meaning "hunt big" or "good hunting grounds". Before the rise of the historic tribes, their indigenous ancestors lived along the river for thousands of years. In the Lower Mississippi Valley, they began building monumental earthwork mounds in the Middle Archaic period (6000–2000 BC in Louisiana). The earliest construction was Watson Brake, an 11-mound complex built about 3500 BC by hunter gatherers in present-day Louisiana. The discovery and dating of several such early sites in northern Louisiana has changed the traditional model, which associated mound building with sedentary, agricultural societies, but these cultures did not develop for thousands of years. The largest such prehistoric mound was destroyed in the 20th century during construction of a bridge at Jonesville, Louisiana. Likely built by the Mississippian culture, which rose about 1000 AD on the Mississippi and its tributaries, this mound was reported in use as late as 1540 by the Spanish explorer Hernando de Soto. On his expedition through this area, he encountered Indians occupying the site. A lightning strike destroyed the temple on the mound that year, which was seen as a bad omen by the tribe. They never rebuilt the temple, and were recorded as abandoning the site in 1736. Land speculators During the late 1700s, when the area was controlled by the Spanish and French, the river served as a route for early colonists, and for land speculators such as the self-styled Baron de Bastrop. The "Bastrop lands" later passed into the hands of another speculator, former Vice President Aaron Burr. He saw potential for big profits in the event of a war with Spain following the Louisiana Purchase. Burr and many of his associates were arrested for treason, before their band of armed settlers reached the Ouachita. During the 1830s, the Ouachita River Valley attracted land speculators from New York and southeastern cities. Its rich soil and accessibility due to the country's elaborate river steamboat network made it desirable. One of the investors from the east was Meriwether Lewis Randolph, the youngest grandson of Thomas Jefferson. He was building a home on the Ouachita River in what is now Clark County, Arkansas, when he died of malaria in 1837. He had been appointed Secretary of the Arkansas Territory by President Andrew Jackson in 1835, and had relinquished his commission when Arkansas became a state in 1836. Steamboats,