The treaty of 1791! You should talk to Stand Watie about how his namesake was a party to the sellout of the Cherokee Nation's lands in Georgia that effectively voided that treaty.
In the 1830s the US bypassed elected Cherokee officials and negotiated a treaty with a small group of others who were not authorized by Cherokee law to sign away Cherokee land. Seems like the treaty was simply a land grab by the government violating the earlier treaty.