threethree

Three comes from Middle English thre, and goes back to Proto-Indo-European *tréyes.

1. Proto-Indo-Europeanc. 4500–2500 BCE*tréyes¹reconstructed
2. Proto-Germanicc. 500 BCE–200 CE*þrīz¹reconstructed
3. Proto-West Germanicc. 200–500 CE*þrīʀ¹reconstructed
4. Old Englishc. 450–1150þrī¹
5. Middle Englishc. 1150–1500thre¹
6. Englishearliest quotation 1912three¹

1. ¹ Wiktionary, English three
2. Earliest quotation in Wiktionary’s entry: 1912, Zane Grey, New York: “Venters began to count them—one—two—three—four—on up to sixteen.”.