Medieval principalities and chiefly families maintained their military groups. This practice of maintaining local militia can be traced back to the period of formation of Nadu in Kerala during the Perumal rule. The Perumal had a capital force of several groups of soldiers under thousand `Nayakas` or `Nair` captains.

Each of these groups comprised of ten soldiers. The function of the fighters was not limited to settling rivalry among political authorities alone. They were invited for settling disputes between ordinary people and this resulted in the emergence of `Ankam`.

The Nairs constituted the important division of the population. They were the knights of the middle ages. They lived upon military service to their overlord. The chief occupation of the Nairs was fighting and they were retained in their service by rulers of different parts of Malabar. They were faithful to their lord that they pledged their life for his sake.

The martial spirit of the soldiers was kept up by several institutions designed specially for that purpose. It is also believed that Cheraman Perumal partitioned the country and introduced the Chekors who were invariably to perpetuate this martial spirit in the Nairs. The Kalari was the most popular institution that braced up the soldiers. Kalari was a school where instructions were given in warfare and letters. The teachers were Nairs and the system worked well so long as they controlled the various activities of the State.

However when the Namboodiris appeared on the scene with their Sanskrit learning, indigenous culture was influenced. Thus Brahmins became the acknowledged teachers and the Nairs were forced to concentrate on military training at the expense of intellectual equipment. The asan or the fencing master supervised the training of the people. This institution was more popular in the north. The Kadathanad locality was known for its great hero named Taccholi Otenan. The Nair soldiers were trained to despise death and regard fighting as a sport.

Naduvali was the chief of the district. The Naduvali was the military chief of his district who was bound to march at the head of his soldiers at the command of the Raja. He would be accompanied by the fighting men under their respective Desavalis. All the soldiers of the district were under his control.