▁been ▁returned ▁through ▁don ation ▁and ▁documented ▁by ▁sch ol ars . ▁ ▁Fund ed ▁by ▁the ▁Works ▁Progress ▁Administration ▁( W PA ), ▁arch ae olog ists ▁from ▁the ▁University ▁of ▁Oklahoma ▁exc av ated ▁parts ▁of ▁the ▁site ▁between ▁ 1 9 3 6 ▁and ▁ 1 9 4 1 . ▁The ▁Oklahoma ▁Historical ▁Society ▁established ▁the ▁S pi ro ▁M ounds ▁Arch ae ological ▁Center ▁in ▁ 1 9 7 8 ▁that ▁continues ▁to ▁operate . ▁The ▁site ▁is ▁listed ▁on ▁the ▁National ▁Register ▁of ▁Historic ▁Places ▁and ▁is ▁preserved ▁as ▁Oklahoma ' s ▁only ▁Ar che ological ▁State ▁Park ▁and ▁only ▁pre - contact ▁Native ▁American ▁site ▁open ▁to ▁the ▁public . ▁ ▁S out he astern ▁Cer emon ial ▁Complex ▁ ▁S pi ro ▁M ounds ▁people ▁participated ▁in ▁what ▁arch ae olog ists ▁call ▁the ▁S out he astern ▁Cer emon ial ▁Complex ▁( SE CC ), ▁a ▁network ▁of ▁cer emon ial ▁cent ers ▁sharing ▁the ▁Mississ ipp ian ▁culture ▁and ▁similar ▁spiritual ▁belief s , ▁cosm ology , ▁rit ual ▁practices , ▁and ▁cult ▁objects . ▁The ▁SE CC ▁was ▁a ▁vast ▁trad ing ▁network ▁that ▁distributed ▁ex otic ▁materials ▁for ▁making ▁rit ual ▁objects ▁from ▁all ▁across ▁North ▁America . ▁These ▁included ▁colored ▁fl int ▁from ▁New ▁Mexico , ▁co pper ▁from ▁the ▁Great ▁L akes , ▁con ch ▁( or ▁light ning ▁wh el k ) ▁shell s ▁from ▁the ▁G ulf ▁Coast , ▁and ▁m ica ▁from ▁the ▁Carol inas . ▁