For as long as humans have lived in settled communities, some groups have sought to assert dominance over others, and through history the biggest empires grew to cover millions of square miles.

When Alexander the Great died in 323 B.C., 13 years after building one of the world's largest empires, he left what would become one of the biggest unsolved mysteries in archaeology. Researchers have ...

For as long as humans have lived in settled communities, some groups have sought to assert dominance over others, and through history the biggest empires grew to cover millions of square miles. But ...