‘Ko-ryu’ refers to a classical Japanese martial school that existed before the Meiji Restoration in 1868. Before this time Japanese society was a feudal system run by Samurai, the warrior class. These societal classes included: Samurai, Farmers, Artisans, Merchants.
As such the martial arts were of primary importance for that ruling class, and permeated almost every aspect of life in Japan. Shinto Muso Ryu Jojutsu (SMR) was developed in that period, specifically by the police of the Kuroda clan in Kyushu, Japan. SMR was actively used by these police, and refined in the course of performing their law enforcement responsibilities, from about 1605 to 1868. See Koryu Primer