ps . ▁ ▁C add o an ▁Mississ ipp ians ▁ ▁Most ▁authorities ▁agree ▁that ▁the ▁people ▁of ▁S pi ro ▁were ▁C add o an ▁speaking , ▁but ▁their ▁descend ants ▁in ▁historic ▁times ▁are ▁difficult ▁to ▁identify . ▁Arch ae olog ists ▁spec ulate ▁that ▁the ▁C add o ▁Confeder acy , ▁W ich ita , ▁K ich ai , ▁or ▁non - C add o an ▁Tun ica ▁could ▁be ▁their ▁descend ants . ▁However , ▁the ▁cult ures ▁of ▁all ▁these ▁pe op les , ▁when ▁encountered ▁by ▁the ▁Spanish ▁and ▁French ▁in ▁the ▁ 1 6 th ▁and ▁ 1 7 th ▁centuries , ▁were ▁substantial ly ▁different ▁from ▁that ▁of ▁S pi ro . ▁ ▁Under ▁the ▁Native ▁American ▁Gra ves ▁Prote ction ▁and ▁Re pat ri ation ▁Act , ▁the ▁C add o ▁Nation ▁of ▁Oklahoma ▁and ▁the ▁W ich ita ▁and ▁Aff ili ated ▁Trib es ▁( W ich ita , ▁K ee chi , ▁W aco ▁and ▁T aw ak onie ) ▁are ▁recognized ▁by ▁the ▁US ▁Federal ▁government ▁and ▁arch ae olog ists ▁as ▁the ▁cultural ▁descend ants ▁of ▁the ▁build ers ▁of ▁S pi ro ▁M ounds . ▁ ▁When ▁the ▁Spanish ▁conquist ador ▁Hern ando ▁de ▁S oto ▁led ▁an ▁expedition ▁into ▁what ▁is ▁now ▁the ▁S out he astern ▁United ▁States ▁in ▁the ▁ 1 5 4 0 s , ▁he ▁encountered ▁Native ▁American ▁groups ▁including ▁the ▁T ula ▁people , ▁who ▁lived ▁near ▁the ▁Ark ansas ▁River . ▁The