Instance Range textures hold a gradient color with a range from 0 - Maximum ID and prepares this range to map to geometric instance IDs. Maximum ID should correspond to the total number of instanced geometry in the scene with the MaterialThe representation of the surface or volume properties of an object. applied on it. Maximum ID values can spread out to allow a wider range of values with less-instanced Objects. Any tools that create instanced Objects in Blender® can communicate with this Node.
Figure 1: Using multiple Array modifiers to apply a gradient across instanced Objects using the Instance Range texture