query: When did the Tango dance develop?
passage: Tango
Tango is a popular partner dance and social dance that originated in the 1880s along the River Plate (Río de Plata), the natural border between Argentina and Uruguay. It was born in the impoverished port areas of these countries, where natives mixed with slave and European immigrant populations.[2] The tango is the result of a combination of the German Waltz, Czech Polka, Polish Mazurka, and Bohemian Schottische with the Spanish-Cuban Habanera, African Candombe, and Argentinian Milonga.[3] The tango was frequently practiced in the brothels and bars of ports, where business owners employed bands to entertain their patrons with music.[4] The tango then spread to the rest of the world.[5] Many variations of this dance currently exist around the world.
passage: Argentine tango
Ballroom tango steps were standardized by dance studios. The steps have been relatively fixed in style for decades. However, Argentine tango has been an evolving dance and musical form, with continual changes occurring every day on the social dance floor in Argentina and in major tango centers elsewhere in the world. Argentine tango dance is, still based heavily on improvisation. While there are patterns or sequences of steps that are used by instructors to teach the dance, even in a sequence every movement is led not only in direction but also speed and quality (a step can be smooth, pulsing, sharp, ... etc.). Although Argentine tango evolves mostly on the dance floor, the government of Argentina does host an annual competition of Argentine tango dance in Buenos Aires, attracting competitors from around the world.