China's actuator supply base is being built by companies arriving from 5 overlapping industrial backgrounds: 1/ Reducer and motion specialists extending their core gearbox technology. 2/ Precision-transmission companies adding actuators, joint modules, motors, drives or roller screws. 3/ Joint-module vendors packaging motors, reducers, encoders and drives into integrated products. 4/ Automotive suppliers expanding into linear and rotary robot actuators. 5/ Linear-motion companies entering through planetary roller screws. The starting point matters because it shapes where each company may have an advantage: precision gearing, module integration, automotive production or linear motion. This map tracks 18 companies and preserves the stage each has disclosed.