The trail of tears as it is called, was the process of mass movement of Native American Peoples form land that the white man wanted for himself; they were sent to Oklahoma, as it was not land no one really wanted, until after the Native Americans were set up there on reservations; when oil was discovered in OK, then the white man wanted that land too.
I have read too, that before the trail of tears, poor whites and blacks started to live with the Native Peoples and the government did not like it, maybe too much power, so they moved them, to separate out the whites and blacks.
My Cherokee and etc mixed lines were fairly light skinned so left for IN and then later came back to MO, then OK, settling in the Chickasaw Territory, but not on Reservation land.
My darker skinned Native lines from upper New England areas, were up in OH, then moved to MO, then to CA.