How did Alexander the Great unify his empire?

Alexander the Great conquered vast stretches of territory. He conquered nearly 3,000 miles in a matter of thirteen years. Unlike other conquered empires, the empire of Alexander the Great was unique in that its conquered residents were relatively united. Alexander the Great was able to accomplish this unity by employing several strategies.
1. He did not want his subjects to think he was trying to exploit them. So instead of destroying local languages, religions, and customs, Alexander preserved local cultures in the areas he conquered.
2. He allowed Persians to serve as administrators in his new empire. This strategy incorporated locals into the decision-making process, enabling them to take part in government.
3. In keeping with his theme of respecting local cultures, he married Eastern women. His wife Roxana was Persian.
These are a few strategies Alexander employed to unite his vast empire despite its size and variety of cultures.