To an English learner, how to use articles (a, an, the) is one of the most difficult things.
Today, I heard an reporter on the radio told about an carnival in New Orleans. He said:
"The little Rascals parade is the largest of the kid parades with nearly 20 floats, marching bands, dancing groups, and Cajun Indians on horseback".
Can I use on the horseback instead of on horseback?