It embodies the inter-city rivalry between Bilbao and Donostia-San Sebastián, respectively the capitals of the neighbouring provinces of Biscay (Bizkaia) and Gipuzkoa in the Basque Country region of Spain.

[1][4] Other clubs in the territory have also competed in the top division (and opposed Real Sociedad occasionally in the second tier, in addition to cup ties), with CA Osasuna, Deportivo Alavés, and SD Eibar the most prominent of these;[3][5] the matches between any of them are also referred to as a “Basque derby”.

However a dispute occurred over the entitlement of Real Sociedad to claim the honour of champions, and two separate competitions were held (both of which were later declared official, meaning there are two 1910 winners).

[26][28] In the 1911 Copa del Rey, Real Sociedad withdrew in protest after their accusations that other teams, primarily Athletic Bilbao, were using ineligible foreign players, were rejected.

At the end of the conflict, the regional championships were re-instated for two further seasons, with Atlético de Bilbao (another renaming, this time an order of Franco's regime prohibiting non-Spanish words that lasted until the 1970s) and Real Sociedad kept apart.

[20] In 1969, the rare possibility of a Basque cup final was ended when Elche defeated Real Sociedad in the semi-finals[42] before losing to Athletic Bilbao in Madrid.

[9][49] In October 1970 the clubs had met in a friendly to mark the installation of floodlights at SD Eibar's stadium, Ipurua, won by Athletic on a penalty shootout after a 1–1 draw.

[20] In 2016, an annual friendly match was established incorporating the results of the Basque derby, as well as other league fixtures between teams in the region, with the two clubs holding the best records being invited to play in the 'final' prior to the start of the following season.

[53] Although Real Sociedad finished 6th in 2016–17, the highest among Basque teams, their record against their neighbours was inferior to those of Athletic Bilbao and Alavés[54] (the match between them in Barakaldo was not completed due to indiscipline among the players).

[65][66] In a tense match featuring several players with ties to the opposition, and which produced many fouls and few chances, Mikel Oyarzabal scored the only goal – from a penalty – to give Real Sociedad a historic victory and their first major trophy since 1987.

[73] Others who made the move, almost all from Real to Athletic, include Luciano Iturrino, David Billabona, Andoni Imaz, Igor Gabilondo, Iñigo Díaz de Cerio, Xabier Castillo, Gorka Elustondo[74] and Mikel Balenziaga.

[78][79] In turn, the buying club only had the sufficient financial means due to receiving approximately double that amount the same day for Aymeric Laporte who moved to Manchester City, also via his release clause.

[80] Real Sociedad's response to the defection of Martínez – who had previously been quoted as saying he would never move to Athletic Bilbao – was to offer a new replica jersey to all supporters who presented an older one with his name on the back at the club shops, with the process titled 'He's history'.

[147] In February 2019, a Basque derby league fixture hosted by Real Sociedad, which would usually be held at the club's Zubieta training centre, was played at the Anoeta Stadium, attracting an attendance of 21,234 (the result was a 2–2 draw).