Short answers, pulled from the story.
Drums made with alligator skins have been found in Neolithic cultures in China, dating to a period of 5500-2350 BC. These are the oldest physical evidence of drum construction, and literary records from the same era describe drums being used in ritual ceremonies with shamanistic significance.
In the Hornbostel-Sachs classification system, a drum is a membranophone, meaning it produces sound through a vibrating stretched membrane. Drums consist of at least one membrane, called a drumhead or drum skin, stretched over a shell and struck to produce sound.
Chinese troops used tàigǔ drums to motivate soldiers, set a marching pace, and call out orders, with drums influencing the outcome of a war between Qi and Lu in 684 BC. Swiss mercenary fife-and-drum corps and English Civil War armies also used drums to relay commands, with different regiments using distinctive beats only their own soldiers recognized. Aztec nations used drums to send battlefield signals, and the Rig Veda records Arya tribes charging into battle to the beat of the war drum called the dundhuhi.
The karyenda was a drum in Burundi that held divine status as a symbol of the power of the king. It elevated the drum from a musical or ceremonial object to a political emblem of royal authority.
Double-ply drumheads dampen high-frequency harmonics and suit heavy playing. Heads with a white textured coating muffle overtones slightly, while heads with central silver or black dots muffle them more. Heads with perimeter sound rings eliminate overtones almost entirely. Single-ply heads with no muffling are preferred by some jazz drummers for their resonance.
Talking drums are drums used in Africa to imitate the tone patterns of spoken language, allowing communication over great distances. The head tension can be changed in performance, as on the talking drum whose top and bottom heads are connected by ropes that a player squeezes to temporarily tighten the head and alter its pitch.