364 km ultra-long Raman fiber laser based on high-order pumping and ultra-low-loss fiber

•The effect of pumping scheme and key fiber parameters to further extend the ultimate length of Raman fiber laser is explored.•The method of combination of higher-order pumping and ultra-low-loss fiber to increase the cavity length of Raman fiber laser is proposed and verified.•A 364 km-long ultra-long Raman fiber laser is demonstrated.