By two thousand years ago, there were large empires right across Afro-Eurasia. They included the Roman, Sassanian, Kushan, Mauryan, and Han Empires. And there were many smaller semidependent states in between. During the next millennium, between two thousand and one thousand years ago, some of the larger empires collapsed, including the largest of all, the Roman and Han Empires. Disease and imperial breakdown slowed growth for almost a millennium.
