I think that the film makes the argument that the validation of voice is a part of the slave experience. I find this very compelling and something that makes understanding the history of slavery even more complex. The film's reconstitution of slavery is not one in which voice is silenced. The institution of slavery is shown as something that actively sought to silence the voices of its targets. Yet, the film depicts individuals in the position of power in terms of activating their own voice against such a predicament. It does not show this arbitrarily. Rather, it shows through struggle and commitment to one's values, even in the horrific condition of slavery, one can cling to one's voice. This is a powerful depiction of slavery. Consider that Shango and Nunu fight against the system. Shola comes to see their sacrifices and she does the same. Mona has effectively gone back in time and understood her own genealogical voice.
In these conditions, the depiction of slavery is shown as a moment in time in which people had to rely on their voice to be heard. The opening line of the film states this very idea: "Spirit of the dead, rise up and claim your story!" Slavery is depicted as a reality in which the reclamation of individual voice is essential to one's humanity. In depicting it in this way, the film causes the viewer to think about the historical condition of slavery.