It is thought that immigrants in Buenos Aires were the first people to play tango; they were called the guardia vieja ("Old Guard"). The style became a favorite among gangsters, who frequented seedy establishments where a complex range of dancing would take place.
A few changes occurred in the 1920s, which didn't just involve the popularity of tango. The double bass was becoming a frequent member in jam sessions and figures such as Carlos Gardel helped to bring the dance into a more classy light. His death marked the crossroads where the dance would split into two different strands.
The golden age of tango was to follow. It involved a good mixture of composers who developed several versions that varied in intensity as well as in difficulty. The milongas are the various styles of music, and many of the originals were quite simple, as they were rather slow. Some of the main composers included Juan Dárienzo, Francisco Canaro and Aribal Troilo.
In future years there was a big focus on Ástor Piazzolla. He wrote "Adios Nonino," which was considered one of the best pieces of tango of all time. In the 1950s you would typically see an attempt to break the restraints of classic tango, spicing the proceedings up with a refreshing jolt. This was certainly achieved in the 1970s, when jazz began to break into tango, creating an interesting fusion.
In modern times, tango has incorporated a wide range of influences, all of which offer a new and refreshing blend.