Actually, a lot of achievements attributed to Arabs in mathematics, astronomy, classical scholarship, etc. was actually the work of Persians (Iranians). A good case in point is Omar Khayam. They're just called "Arabs" because when Persia adopted Islam, the people adopted Arab names.
Islam conquered the Persian civilization and then claimed all of its intellectual achievements as its own; and “Muslim” civilization of the last 800-1200s were the flowering of Persian thought and Iraqi civilization through cultural exchange until it converted wholly to Islam, suffocating it.