Where did the kickapoo come from?

The Kickapoo or Kiwikapawa people were originally part of the Wabash confederacy of tribes, along with the Piankashaw, Miami and Wea. Their language is classified as central Algonquian, very closely related to Sac and Fox and the Illinois language.

They were first mentioned by French explorers, situated between the Wisconsin and Fox rivers.

There is nothing to suggest that they "descend from an ancient tribe"; they certainly belong to the Algonquian linguistic stock, but their ancient ancestors are unknown.