You may as well point fingers at all the various Islamic, Indian, African, or even indigenous "Amerindian" empires then. But your whataboutism ignores the fact that these empires were vastly different from the system of imperialism as practiced by the west.

It's like saying "black people enslaved other blacks too," or "what about the Arab slave trade," or "indigenous peoples killed each other all the time." Sure, but the specifics of how the west did it are a world of difference, and you're a racist for saying it that way.