What is the central idea of “the unspoken history behind a surname”

That there is a hidden meaning behind the last name of African American people in United States that can be tracked back to slavery days.

Explanation:

In “The Unspoken History Behind a Surname”,  writer  Lolly Bowean stated that many of the surname that held by African Americans were actually given during the slavery days.  

In the past, Slave owners wanted to make it easy to identify the slaves that they owned. So they change the name of African Slaves to the name that is common in western hemisphere.

She used her surname as an example. Bowean was a name of a small city where a slave plantation once located. The owner change her ancestor's name to signify that her ancestors belonged to the plantation.

the name of the theory is landmass theory.

sitting in that one chair where he could get shot at was his worst decision.