The origin of Cha Cha, is Guajira ( breaks on "1" ) and also danced in mambo,old school, called triple Mambo .Guajira is also a dance in its own right .
Latin music ( Son Rhythms ) are quite specific in their intent, and Guajiras, to many, may sound like Cha Cha,to which one may dance Cha Cha.. but.. the Cha Cha composition only has one syncop. action which " joins " 2 bars together, if you will as in 4and 1.
The syncop. in Guajira, is included in the same bar.. 1,2,3and4. There is frequently a 2nd syncop. , that is not as dominant on the 2nd bar .
The commencement of Cha Cha, differs between the Amer. style and Intern.
Amer. style commences its break, back, as opposed to the Intern. styles Fwd break. Both are " prepped " on 1 .
Chas back break beginning, is using the same format, as Mambo and Bolero ,in the Amer.style dances.
If you want to hear what a classic Guajira sounds like, check out " Guantanamera ".. there are numerous recordings ( believed to be the most recorded song in the genre ).