The oriential memory approach may have existed since Ming dynasties, 45 centuries ago. But the orientals did not really left a very detailed, rigorous science of memory. Buddha is supposed to be the Enlightened one. But his adherents forgot to leave many “enlightening” details on the art of remembering.
Hence, the Simonides tale is correctly overemphasized, because he made a total Paradigm Shift for the future millenia of mnemonics. Someone had to be first, in the areas of rigorous scientific discovery. And in the areas of mnemonics in particular it was the Greco-Roman intelligentsia to break through first. That’s known history.