Have made many posts about the construction of latin music..  simply put...
       music with a syncop within the bar, as in 1.2 3 and4.. is guajira.. this is the ORIGINAL latino form of which also transpired into Cha.written with a different accent .
                     the " form " is tied up with Danzon .. the structure that evolved  from that ( the current style of Bolero and Intern Rumba ) was transformed from the originator of mambo music... Cachao... it became a clave driven 2 bars known simply as rumba clave.
the dance sequence became Triple Mambo to Guajira to Cha  .
                
The cuban singer Guillermo Portabales was responsible for refining the rhythm  to " salon guajira " .( done in a 3/4 and 6/8 time sign.)
many cubans today, still break on 1 irrespective of the clave change .They incidentally  call the mambo, Systemo Cubana .
 to add to this, it is all underpinned in " son " rhythm brought to cuba by 2 dominican sisters in the 1800s .This the driving force behind ALL latin rhythms .
                  the history and origins are very complex,so one should  read and research why we use the rhythms we choose ( santeria, the religion , has a large part to play in the mix ) 
         As one can see.. just saying oh.. break on 1 or 2, it doesnt matter , is contrary to all that the genre is based upon. Even the direction in which we start is important .
                  if you need Guajira songs, they crop up from time to time in salsa recordings. 
                    the latest " Classic " is by Cachao, which was recorded just before his death early this yr . ( it has a DVD set ).
This is a truly amazing experience, introduced by none other than a famous Cuban  Hollywood star .