What are the purposes of the laws congress passes?

The purposes of laws that congress passes are to carry out their Constitutional duty to govern the United States through legislation. Congress is charged in the Constitution to be the official legislating body in the United States and to write legislation to govern the American people. This legislation takes on many forms from signing treaties, to releasing government funds to pay for programs, to many other areas of American life as well. 

Cherokee  removal, part of the trail of tears, refers to the  forced  relocation between 1836 and 1839 of thecherokee  nation from  their lands ingeorgia, south carolina, north carolina, tennessee, texas, and alabama to the indian territory (present day oklahoma)  in  the thenwestern united states, and the resultant deaths