Probably in the early 13th century, close to 1200. It's included in W2 along with several three-part conducti and organi from the "Notre Dame school" of polyphony.
I recall reading that the text of "O Maria virginei" has been loosely ascribed to Philippe the Chancellor (of Notre Dame de Paris), who also wrote "Beata viscera" (set to music by Perotin).
O Maria Virginei is a traditional Marian hymn that has been passed down through generations, so its exact date of composition is unknown. It is believed to have originated in the medieval period in Europe.
Maria Granovsky has written: 'Studies on O-glycan biosynthesis'
Maria Clovis has written: 'Caudilhos, ou, O inferno dos deuses'
Maria Esther Maciel has written: 'O livro dos nomes'
Maria Teresa Bijos Faidiga has written: 'O produtor rural e o imposto de renda'
Maria Helena Maia has written: 'Um tecto para o universo'
Ana Maria Miranda has written: 'Noturnos' 'Sem pecado' 'Clarice Lispector' 'O retrato do rei'
Giovanni Maria Cecchi has written: 'Comedie di M.Gianmaria Cecchi...' 'Lezione, o vero Cicalamento'
Maria Isabel Barreno has written: 'New Portuguese letters' 'Vozes do vento' 'O mundo sobre o outro desbotado' 'Novas cartas portuguesas' -- subject(s): Accessible book 'O senhor das ilhas'
Rosa Maria Sousa Martins Rocha has written: 'O mar territorial' -- subject(s): Maritime law
Maria Berenice Dias has written: 'O terceiro no processo' -- subject(s): Third parties (Law), Intervention (Civil procedure)
Ana Maria Domingos has written: 'Uma forma de estruturar o ensino e a aprendizagem' -- subject(s): Curriculum planning
Suzana Albornoz Stein has written: 'O caso Legiani' 'Maria Wilker'