▁ 1 5 ▁feet . ▁The ▁to ps ▁of ▁the ▁stones ▁can ▁be ▁flat , ▁round ▁or ▁sm ashed , ▁suggesting ▁that ▁perhaps ▁the ▁original ▁top ▁had ▁been ▁deliber ately ▁destroyed . ▁The ▁stones ▁are ▁usually ▁orient ed ▁with ▁the ▁decor ated ▁face ▁to ▁the ▁east . ▁ ▁The ▁car v ings ▁and ▁designs ▁were ▁most ▁usually ▁completed ▁before ▁the ▁stone ▁was ▁ere cted , ▁though ▁some ▁stones ▁show ▁signs ▁of ▁being ▁car ved ▁in ▁place . ▁The ▁designs ▁were ▁pe ck ed ▁or ▁ground ▁into ▁the ▁stone ▁surface . ▁Deep - gro oved ▁cut s ▁and ▁right - angle ▁surfaces ▁indicate ▁the ▁presence ▁of ▁metal ▁tools . ▁Stone ▁tools ▁were ▁used ▁to ▁smooth ▁the ▁har sh ▁cut s ▁of ▁some ▁designs . ▁Near ly ▁all ▁the ▁stones ▁were ▁hand ▁car ved , ▁however ▁some ▁unusual ▁stones ▁show ▁signs ▁that ▁they ▁could ▁have ▁been ▁cut ▁with ▁a ▁primitive ▁type ▁of ▁mechanical ▁dr ill . ▁ ▁Types ▁of ▁stones ▁ ▁V . ▁V . ▁Vol kov , ▁in ▁his ▁thirty ▁years ▁of ▁research , ▁class ified ▁three ▁distinct ▁types ▁of ▁de er ▁stones . ▁ ▁Classic ▁Mong ol ian ▁These ▁stones ▁are ▁fairly ▁detailed ▁and ▁more ▁elegant ▁in ▁their ▁dep iction ▁methods . ▁They ▁usually ▁feature ▁a ▁bel ted ▁war rior ▁with ▁a ▁st yl ized ▁flying ▁rein de er ▁on ▁his ▁tor so . ▁ ▁This ▁type ▁of ▁stone ▁is ▁most ▁prominent ▁in ▁southern ▁Si ber ia ▁and ▁northern ▁Mong olia . ▁This ▁concentration ▁suggests ▁that ▁these ▁stones ▁were ▁the ▁origin ▁of ▁the