Complex sentence: The knowing of the concept of miasma can separate into several steps, first, before Western Jin Dynasty, the concept of miasma was gradually forming; at least, in Eastern Han Dynasty, there was no characters of miasma.
Split into simpler sentences: The knowing of the concept of miasma can separate into several steps. First, before Western Jin Dynasty, the concept of miasma was gradually forming; at least, in Eastern Han Dynasty, there was no character of miasma.