Complex sentence: The Arabs did not use the name "El-Barbar" as a negative name, because the ancient Arab historians were not aware of the origin of that name; so, they created some myths or stories about the name.
Split into simpler sentences: The Arabs did not use the name "El-Barbar" as a negative name. Because the ancient Arab historians were not aware of the origin of that name, they created some myths or stories about the name.