Symbolism, Imagery, Allegory
Before the iPhone, before the Android, and even before that wonderful, early-2000's hunk of junk known as the Razr, it was pretty hard to communicate with other people.
Really hard, in fact. In Roots, we see one innovative method for communication in the pre-smartphone world: music.
In Kunta's West African homeland, music is literally used as a communication device. This is known as drum talk: villages can communicate with one another by playing precise drum patterns that mimic the Mandinka language. It's super amazing. With this method, messages can be transmitted across vast distances more quickly than thought possible at the time.
After being brought to America, Kunta notices that the other people enslaved here aren't allowed to have drums and wonders why.
Take a look:
Was it because the toubob knew and feared how the sound of the drums could quicken the blood of everyone in the village, until even the little children and the toothless old ones would dance wildly? [...] Or perhaps the toubob were simply afraid to allow a form of communication they couldn't understand that could travel the distance between one farm and another. (46.9)
We think you hit the nail on the head, buddy.
Despite this, music is still being used as a communication tool in America, just in a slightly varied form. Think about how the imprisoned women on the slave ship would give details of its layout to the men through song. Or think about how Kunta suspects that the slaves are transmitting messages through their singing. Thankfully, this tradition is alive and well, even if it's adapted into a different form.
Besides being important on a cultural level, music provides enslaved Africans a way to secretly communicate with one another, retain a small part of their cultural heritage, and instill a sense of unity. And we think that's way better than getting a new rose gold iPhone.