We propose and experimentally demonstrate a long-range Brillouin optical correlation domain analysis (BOCDA) system based on distributed Raman amplification and injection-locking to reach over 2.6 million resolving points. The optimization of key parameters in the Raman amplification, time domain data processing, differential measurement scheme, and injection-locking are applied to achieve a spatial resolution of 2 cm over a 50 km sensing fiber. Our result corresponds to at least twice improvement compared to former records, and the best one among distributed Brillouin sensors in terms of the number of resolving points.