Sriraman Bhattachar Swami is the chief priest of the Devadiraja Perumal Vishnu temple in Therazhundur, which is the birthplace of Kamban, the Sri Vaishnava poet who composed the famous Kamba Ramayana. In any case, at around the 6 minute mark of this lecture, Sriraman Bhattachar Swami says this (translated from Tamil):
In regard to Ravana’s Mulabala battle, it is said that he was keeping all his Mulabala forces in one place. That Alaya became after some time called Australia - they say Astralaya changed into Australia.
Ignoring the Australia part, I’m interested in the rest. Mulabala means root strength and it refers to the core forces of Ravana’s Rakshasa army. At one point during the war with Rama, Ravana got desperate and sent his entire Mulabala forces to fight Rama, but Rama singlehandedly defeated them as described in this chapter of the Yuddha Kanda of the Ramayana:
A hundred monkey-chiefs rushed towards each single demon in the battle, even as birds would rush towards a tree laden with fruits. Then, the demons resembling mountain in size, struck down the terrific monkeys with large maces, darts, swords and axes. The huge army of monkeys, being struck down by the demons, sought refuge in Rama, the son of Dasaratha, who affords protection. Thereupon, Rama of great splendour and prowess, taking up his bow and entering the army of demons, streamed forth showers of arrows. Those highly terrific demons dared not approach Rama, having entered their ranks, was scorching them with the flame of his arrows, even as clouds would not approach the scorching sun in the sky. Those demons saw the most terrible deeds only of Rama, when they were actually performed by him in the battle-field, which were difficult to perform for others. Those demons could not actually see Rama, while he was shaking their huge army and blowing away their great chariots, any more than one could see a gale of wind in a forest. They saw the army torn and pierced with arrows, as also scorched, broken down and tormented with missiles. They could not see Rama, who was so swift in his martial art. The demons could not behold Rama hitting their bodies, even as created beings are not able to see their individual souls resting in their sense-objects. "Here is Rama, killing the army of elephants. Here is Rama, destroying great chariot-warriors. Here is Rama, killing foot-soldiers along with horses with his sharp arrows". Saying so, all those demons struck one another with rage in the battle-field those who were in similarity of appearance to Rama. Having been thrown into confusion by the great mystic missile presided over by the Gandharvas , the celestial musicians; presided over by the Gandharvas , the celestial musicians; those demons were unable to see Rama, even when he was scorching away their army. Those demons for their part saw thousands of Rama's in the battle-field, while at other times, they saw only one Rama in that great battle. Those demons for their part saw thousands of Ramas in the battle-field; while at other times, they saw only one Rama in that great battle. The created beings saw that Rama in the form of a discus, which was killing the demons on the battle-field, like the "Wheel of Time", for its flame, the arrows for its spokes, his bow for the felly of the wheel, the twanging of the bow-string and the clanging of the gauntlet for the sound produced for its revolution, his energy and the virtues for its radiance and the power of his mystic missiles for its edge.Within a matter of three hours, with his arrows looking like tongues of flames, Rama killed an army of demons, capable of changing their form at will, including ten thousands chariots possessing the swiftness of the wind, eighteen thousand strong elephants, fourteen thousand horses with their riders and a full two lacs of demons fighting on foot. Those surviving demons, with their horses killed, with their chariots destroyed, with their flag-staffs broken and with broken spirits, rushed back towards the City of Lanka. That battle-field, with elephants, foot-soldiers and horses killed, looked like a pleasure-grave of the powerful and the enraged the lord of destruction. Then, the celestials along with Gandharvas the celestial musicians, holy saints and great sages acclaimed that feat of Rama, saying "well done, well done! ".
But my question is, where did Ravana have his Mulabala forces stationed before he deployed them against Rama? It presumably wasn’t Australia, but do any scriptures mention the location?