Complex sentence: Between 1886 and 1890, numerous mining communities developed in the canyon that were the sites of several labor disputes, namely the Coeur d'Alene labor strike of 1892 and the confrontation of 1899, which resulted in violent conflict between miners and mine owners.
Split into simpler sentences: Between 1886 and 1890, numerous mining communities developed in the canyon. The communities in the canyon were the sites of several labor disputes, namely the Coeur d'Alene labor strike of 1892 and the confrontation of 1899, which resulted in violent conflict between miners and mine owners.