Musicals came to us from opera which came to us from earlier forms of musical plays.
History of opera:
History of OPERA including Roman revivals and intermezzi...., Dafne, Monteverdi, Dido and Aeneas, Handel, Gluck and the reform of opera, Mozart and opera, ...
Opera - Wikipedia, the free encyclopedia
Earlier models of opera generally stuck to more distant history, .... Oxford Illustrated History of Opera, Chapter 1; articles on Peri and Monteverdi in The ...
Brief History of Opera. Lesson Connection: Aida and Its Relevance to the World Today. Copyright The Kennedy Center. All rights reserved. ...
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Metropolitan Opera History
Profiles of famous Met singers, such as Mathilde Bauermeister, Celestina Boninsegna, Ferruccio Tagliavini, and Lawrence Tibbett.
History of Classical Music - Eras
Musical history during the Medieval Times, Renaissance, Classical Period, Baroque, ... (e.g. Handel's Water Music), or as a spectacle in the form of opera. ...
Here is a site that shows the development from opera to operetta to musical.