combined vertical and horizontal integration
Answer:
In the establishment of the African diaspora, the transatlantic slave trade is often considered the defining element, but people of African descent have engaged in eleven other migration movements involving North America since the 16th century, many being voluntary migrations, although undertaken in exploitative and hostile environments.
The Ancient Mayans developed the science of astronomy, calendar systems, and hieroglyphic writing. They were also known for creating elaborate ceremonial architecture, such as pyramids, temples, palaces, and observatories.