1) Gunpowder
The Ottoman, Safavid, and Mughal empires rose as great powers and expanded largely during the 16th century due to a great extent to the use of gunpowder weapons. Armies from the three empires acquired this new military technology which resulted very useful for their campaigns and for keeping the power.
2) Strong political leadership
The three empires experienced an era of expansion under the rule of strong emperors: Suleiman the Magnificent in the Ottoman Empire, Shah Abbas I in the Safavid Empire, and Akbar in the Mughal Empire. The three of them carried out political, legal, economic, and military reforms and led their empires during a time of cultural bloom and economic growth.