Complex sentence: This ranking system was introduced by Kanō Jigorō, the founder of judo, in 1883 and the first "dan" grades were awarded to his students Saigō Shirō and Tomita Tsunejirō.
Split into simpler sentences: This ranking system was introduced by Kanō Jigorō, the founder of judo, in 1883. The first "dan" grades were awarded to his students Saigō Shirō and Tomita Tsunejirō.