What this song renders
The scene the song renders is the single most famous moment in the whole record of Tomyris, and it comes from Herodotus alone. After the Massagetae destroy the larger part of the Persian army and Cyrus falls, Tomyris has the field searched for his body. When it is found she has the head struck off and pushes it into a wineskin she has filled with human blood — ‘I warned you I would give you your fill of blood, and so I shall’ (Herodotus 1.214). The line the album sets — ‘You thirsted for blood, Cyrus. Now drink your fill’ — is the compressed, address-form version of the same speech.
Herodotus himself flags the limit of his own report. Having given this version of Cyrus’s death, he adds that ‘of the many accounts of how Cyrus died, this seems to me the most credible’ — an admission that other deaths circulated. Other ancient writers have Cyrus die elsewhere and otherwise; Xenophon gives him a peaceful end in bed. So the wineskin is the best-attested version of a contested death, not a fact beyond dispute — but it is the version that fixed Tomyris in the Western imagination for two and a half thousand years.
The song renders the keeping of the vow, not the gore. The head-severing and the filling are withheld; what the track holds is the calm — the woman kneeling in the dust, taking the skin, making no sound, collecting a debt she swore in Track 05 to collect. The chorus mutates from the word is kept to I keep my word: ritual closure becoming a colder first-person claim, and then the bridge crossing, and then silence.
The wineskin and the ‘drink your fill’ speech come from Herodotus 1.214, who calls it the most credible of several accounts of Cyrus’s death — so it is best-attested, not undisputed (other ancients, e.g. Xenophon, give Cyrus a peaceful end). The lyric quote is the compressed address-form of the Herodotus speech. See Truth & Legend.