The concept of fortification during the Middle Ages was not very different from that in ancient India. There was noticed an increased tendency to construct hill-fortresses. Of the numerous hill-fortresses existing in northern India at the time of Muslim invasions, the most

famous were:

Loharakotta	Sirahsila	Kangra (Nagarkot)	Chittorgarh	Mandor	Kalinjar (Kalanjar)	Maniyagarh
Bansala	Bhira (Bhatia)	Ajayameru	Ranthambore	Gwalior	Ajayagarh

The first three from the list mentioned, were erected in Kashmir. Muslim historians have referred to some of these forts in terms of shimmering admiration and glory. According to the Prabhavakacarita, the strong fortification of Ajmer (Ajayameru), the capital of the Cahamanas, consisted of a sixteen-mile-fence of acacia, khadira, badari, and other thorny bushes. And this prolonged fence had on one occasion kept the Chalukya forces of Gujarat at bay and compelled them to retreat.

Besides hill forts, the practice of constructing defensive works around cities in the plains was also common. Muslim chroniclers refer to a number of fortified cities, as Delhi, Kanauj, Multan, Jalor (Jalawar), Asni, Thangar, Kol, Mirat (Meerut), etc. Delhi has been described as one `among the chief (mother) cities of Hind, consisting of a fortress which in height and breadth (had) not its equal throughout the length and breadth of the climes.` Kanauj is believed to have consisted of seven isolated forts. The fort of Multan had a large city commanded by a citadel which had four gates and surrounded by a moat. Jalor (Jalawar) is referred to as a strong fort with gates and bastions and Thangar as a `fortress which resembled a hill of iron`. The art of warfare during Middle Ages had by the mid-era turned into a gargantuan occasion, which perhaps remains unrivalled even to these times.

With the growth of the feudal conditions, the number of forts and fortresses had considerably increased. The Chachnama has enumerated a large number of them in the kingdom of Dahir (eighth century) in Sind. The Samarangana-sutradhard of Bhoja reveals that a considerable part of the kingdom was invaded by chiefs who dwelt in forts.

The Krtyakalpataru enumerates detailed directions for equipping a fortress. Craftsmen of all kinds, soldiers, cattle, horses as well as elephants, ordnances of war, including siege-engines and weapons and different kinds of food materials were preserved inside. Men from the medieval period were true to their belief in supernatural agencies and miracles. Such a belief in ritualism as a means of defence was likely to lead to the neglect of its military aspect. The Harihara-caturahga, a later work, brings into prominent relief the same tendency, where the list of six types of forts includes a type called dharmadurga, i.e. a fortress guarded by ritualism.