Complex sentence: In early days the travel routes to the far West were infested by highwaymen, who, however, seldom united into bands, and such outlaws, when captured, were often dealt with in an extra-legal manner, e.g. by "vigilance committees".
Split into simpler sentences: In early days the travel routes to the far West were infested by highwaymen, who nonetheless seldom united into bands. Such outlaws, when captured, were often dealt with in an extra-legal manner, e.g. by "vigilance committees".