Arabic language was at its peak in 6-7century AD and one meaning of word "ajamee= non arab" in classical arabic is a person who is unable to speak, illiterate, not-fluent and it was this time when Quran was revealed and Allah challenged them to produce a Surah like it but even those masters of arabic poetry were not able to do so. Arabic is both poetic(hypnotical) and commanding at the same time.
Also all 4 major books were revealed in semitic languages