Why did the trans-atlantic slave trade expand after the 16th century?

The Atlantic slave trade, also known as the transatlantic slave trade, refers to the slave trade that took place across the Atlantic Ocean between the 16th and 19th centuries. The vast majority of the slaves involved in the Atlantic traffic were Africans from the central and western parts of the continent, mostly prisoners of the wars between rival ethnic groups that were sold by African slave traders to European buyers, who transported them to their colonies in North and South America. There, the slaves were forced to work in the plantations of coffee, coconut, tobacco and cotton, in the gold and silver mines, in the rice fields, in the construction industry, in the wood, in the construction of boats and in homes as servants.

The European colonialists initially practiced a system at the same time of forced labor and slavery of Native Americans, enslaving most of the natives of the New World. For different reasons, Africans replaced Native Americans as the main enslaved population of America. In some cases, such as that of the Caribbean islands, wars and diseases such as smallpox eliminated the natives completely. In other cases, such as in South Carolina, Virginia and New England, the need for alliances with native tribes coupled with the availability of African slaves at affordable prices led to the progressive demise of Native American slavery.

a stronger central government  

its what they are

both eastern and western early north american cultures were known for building wigwams and longhouses.

wigwams, also called wetus, were small houses of 8-10 feet tall, made of wooden frames covered with woven mats and sheets that were used by algonquian indians. similarly,   longhouses were also used by algonquian and the iroquois tribes, and they were built as well with pole frames and elm bark covering. however, the main difference between wigwams and longhouses is that the latter was much larger than the former, with 200 feet long, 20 feet wide, and 20 feet high with inner raised platforms used for sleeping space.