Hi, I'm new to the forums, so I'm not entirely certain if this is the right place for this, but I found some incorrect information on the page titled "American Indian culture of the Northeast", linked here:

https://www.khanacademy.org/humanities/us-history/precontact-and-early-colonial-era/before-contact/a/northeast-indian-culture

It says "Hopewellian culture began the tradition of mound-building...", however this is untrue. The preceding Adena culture built mounds and actually inherited the tradition from North America's archaic period. Some researchers date the first mounds to around 4500 BCE, which is over 4,000 years before the Hopewellian culture emerged.