The period of tango history called guardia vieja can be divided in two stages. One where tango emerges as a distinct musical genre but is still executed by solo performers or casual trios and cuartetos. And a second phase where the traditional orquestas típicas progressively takes shape.
According to Horacio Ferrer and the Academia nacional del tango, these two phases are the Eclosión phase (1895-1909), which begins with the creation of tango as distinct and documented musical genre, and Formalización phase (1910-1925) which begins with the introduction of the bandoneon and the creation of the first specialized tango orchestras.
During the eclosión phase, tango becomes a historical reality with the first documented mention of a tango criollo in a zarzuela entitled “Justicia Criolla”. At the same time “El entrerriano” by Rosendo Mendizabál becomes the first published tango with printed partitions and a registered author. Other early tangos which were published shortly after and contribute to defining tango as distinct musical genre are “Don Juan”, “El Choclo” and “La Morocha”.
In the early stage of the formalización, the bandoneon is introduced in tango instrumentation and becomes a characteristic element of the first orquestas típicas, such as those of Vicente Greco and Juan Maglio. Because the bandoneon is a rare and difficult instrument to master, it becomes the signature of an orchestra dedicated to tango music.
With the introduction of the bandoneon, an important change occurs in the feeling and the sound of tango. Flutes and guitars are left behind and tango begins to take deeper and more melancholic tones. The piano is introduced to tango orchestras by Roberto Firpo in 1912 and the double bass is added by Francisco Canaro. This completes the creation of a traditional sexteto which is composed of two bandoneons, two violins, piano and double bass.
During the guardia vieja, tango not only reaches a broader audience in Buenos Aires cafes and nightclubs, but also in Paris where tangomania begins, soon to reach other parts of Europe and the United States. Some of the musicians, signers and dancers who first took tango to the old world include Ángel Villoldo, Los Gobbi and Casimiro Ain.