user: Question: Which removal treaty covered the Chickasaw nation?
Columns: ['Nation', 'Removal treaty (year signed)', 'Years of major emigration', 'Total number emigrated or forcibly removed', 'Number stayed in Southeast', 'Deaths from warfare']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Choctaw', 'Dancing Rabbit Creek (1830)', '1831–1836', '12,500', '7,000', 'none']
SQL:

assistant: SELECT "Removal treaty (year signed)" FROM "Table" WHERE "Nation" = 'Chickasaw';