Answer by taking a quote from the following article:

Thalia was born on 26 August 1971, in Mexico City, Mexico. She is the youngest of five daughters of Yolanda Miranda Mange (d. 2011), a painter who was Thalia's manager from 1980 to 1999; and Ernesto Sodi Pallares (d. 1977), a scientist, doctor of pathology, criminologist, and writer. Her four sisters are Laura Zapata (daughter of Guillermo Zapata Perez de Utrera), Federica, Gabriela, and Ernestina Sodi. When she turned one, Thalia appeared in her first TV commercial in Mexico.

In 1981, when Thalia was nine years old, she was incorporated as a vocalist in a children's group named Pac Man, which was formed in order to participate in a popular music festival known as Juguemos a cantar ("Let's play while singing"), a TV program by Televisa. Later, Pac Man changed their band name to "Din-Din". Thalia performed various times along with Din-Din in occasional events and parties, touring all over Mexico. The band recorded a total of 4 studio albums between 1982 and 1983 (En accion, Recordando el Rock and Roll, Somos alguien muy especial and Pitubailando), and later it was disbanded.  After Din-Din broke up in 1984, Thalia participated as a solo artist in two annual music festivals of Juguemos a cantar. In 1984, she placed second there with her interpretation of "Moderna nina del rock" ("Modern rock girl"); this brought her the opportunity to participate in the chorus of the popular musical Vaselina, a child version of the successful musical Grease, in which the band Timbiriche was acting and singing. The line-up of the band consisted of Sasha Sokol, Benny Ibarra, Erik Rubin, Diego Schoening, Mariana Garza and Paulina Rubio. Timbiriche was highly promoted at the time by Televisa, one of the most massive media enterprises globally and the most important in the Spanish-speaking world. Some time later, Thalia obtained the protagonist role of Sandy Dee in the musical, and she performed in 500 theater presentations of Vaselina along with Timbiriche.  In 1986, after the departure of Sasha Sokol from Timbiriche, Thalia became a member of the band. By that time, Timbiriche had already recorded five albums. In the following year, Thalia was invited to participate in the telenovela Pobre senorita Limantour; this production was actually Thalia's debut as a TV actress. However, she appeared in only one episode. In the same year, she recorded with Timbiriche the principal theme of the juvenile telenovela Quinceanera ("Fifteen-year-old"), in which Thalia was the co-protagonist with the role of Beatriz. The TV series was awarded as the "Best telenovela" by "Premios TVyNovelas" in 1988 and Thalia was awarded as "the best new actress of 1988".  With Timbiriche, Thalia recorded four studio albums: Timbiriche VII (1987), the double album Timbiriche VIII & IX (1988) and Los clasicos de Timbiriche (1989). The last one is a compilation of the band's greatest hits, recorded originally in 1987, with new symphonic arrangements as it included the participation of Mexico's philharmonic orchestra. In 1989, Thalia departed from Timbiriche. In that year, she also starred in another TV series, Luz y sombra ("Light and shadow"), which was her first protagonist role. Some time later she visited Los Angeles in order to take English courses in the University of California. She also attended music, singing, acting and dancing classes before beginning her career as a solo artist.

What is the Timbiriche Era?
In 1986, after the departure of Sasha Sokol from Timbiriche, Thalia became a member of the band.