Complex sentence: Since the arabs didn't encourage non-arabs to learn their language so that only arabs can take high postions in the government, he was the first non-arab to write on arabic grammer and therefore the first one to explain the arabic grammer from a non-arab perspective.
Split into simpler sentences: Since the arabs didn't encourage non-arabs to learn their language so that only arabs can take high postions in the government. He was the first non-arab to write on arabic grammer and therefore the first one to explain the arabic grammer from a non-arab perspective.