He mentions no predecessors. Diogenes Laertius, writing centuries later, credits only Zeno as a master of Leucippus. As little as is known about Leucippus, less is known about Kanada. However, Horne goes on to discuss the Samkhya-system, thought to be the oldest of the six fundamental interpretations of Ultimate Reality. It holds that there are five subtle particles corresponding to the five elements and derived by processes of differentiation and unequal aggregation from a super-subtile, homogeneous rudimentary matter.
Greek atomism is related to the problems which pre-dated it.
It appears to the writer, who is no expert on the matter, that atomism arose essentially simutaneously in the West and in the East. It is interesting that Greek atomism arose in the easternmost regions. I feel this is no argument for atomism starting in India and being transmitted to Greece. Rather that the intellectual climate in that part of the world about 2500 years ago was ripe for this particular idea. As has happened so often in science, atomism was discovered at the same time in two locations.