The period of tango history called guardia vieja can be divided into two stages: in the first, tango emerges as a distinct musical genre or “tango criollo” and, in the second, the initial trios and cuartetos evolve progressively into orquestas típicas.
According to Horacio Ferrer and the Academia nacional del tango, the two phases of evolution of the guardia vieja are:
- Eclosión (1895-1909)
- Formalización (1910-1925).
During the eclosión phase, tango becomes a historical reality with the first documented mention of a tango criollo in a zarzuela entitled “Justicia Criolla”. In the same period “El entrerriano” by Rosendo Mendizabál becomes the first printed tango partition with a registered author. Other early tangos with printed partitions that contribute to defining the genre at this early stage include “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 which were dedicated exclusively to tango. The sound of tango evolves substantially as flutes and guitars are left behind and the piano is introduced to tango orchestras by Roberto Firpo in 1912.
Another important figure of the guardia vieja is Francisco Canaro who introduces the double bass to the orquesta típica, completing the creation of a traditional sexteto composed of two bandoneons, two violins, piano and double bass.
The guardia vieja is also a phase where tango begins to reach a broader audience in Buenos Aires cafes and nightclubs and abroad where tangomania begins spreading from Paris to 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. π
 Ferrer, Horacio. El Siglo de oro del Tango: compendio ilustrado de su historia. Buenos Aires: Editorial El Mate, 1996. Print.
 Amuchastegui, Irene. “El día en que el tango tuvo nombre.” Clarín [Buenos Aires] 28 Sept. 1997. Web, 1 Aug. 2016.
 Pesce, Ruben. La Historia del Tango: La Guardia Vieja. Corregidor, 1977. Print.
 Zalko, Nardo. Paris / Buenos Aires: Un siglo de tango. Buenos Aires: Corregido, 2001. Print.