It is no accident that the three most attacked books of the Bible are also the most significant (Genesis, Daniel, and Revelation).
Liberal scholars advocate the idea that since Alexander the Great did not spread the Greek language until the fourth century, Daniel could not have been written in the sixth century.
English versions of the Bible are based on the canonical order given in the LXX.
As such, Daniel is grouped with the three major (writing) prophets.
Critics charge that the sixth century is too early for that word to have developed into a term that refers to a certain group of men. In some of his writings he refers to the Fourth, it has been noted that the Book of Daniel has at least a few words from four different languages.
Persian, Greek, Hebrew, and Aramaic are all represented.