After Rama killed the demoness Thataka, Viswamitra gave him a lot of asthras and taught him how to use them. Then they reached a place which appeared very pleasant with trees in full bloom, singing birds, plants and creepers. Rama was enamoured by it's beauty and enquired of Viswamitra about the place. The latter replied that it was the place where the protector of the universe Lord Mahavishnu attained Siddhi in Vamana Avathara and that the place was called Siddhashrama. He further added that he had chosen this place to perform yaga (sacrifice) and that the demons were spoiling his efforts. He expressed his desire that they should be killed in the very same place.

They entered the Siddhashrama where they were received by the other rishis. Rama requested Viswamitra to begin his yaga. The yaga was to be performed continuously for six days. Both Rama and Lakshmana with bow and arrow guarded the sacrificial hall day and night without sleep. Five nights passed peacefully without any hindrance, but on the sixth day the two demons Subahu and Mareesan tried to pour blood from the sky. But before it could harm the sacrifice, Rama with his Manavasthram stopped the rain of blood and hit Mareesan on his chest. The asthra numbed his mind, carried him and dropped him in the Sea. Rama killed Subahu and the other demons using other asthras.

Thus Rama helped Viswamitra finish his yaga peacefully. The next morning after finishing their ablutions, they were told by the other rishis that they were leaving for Mithila where King Janaka was planning to perform a grand sacrifice. They informed that King Janaka possessed a bow called 'ShivDhanush' which no one can string regardless of either they were humans or demons or devas. The rishis invited Rama and Lakshamana to come and see the Bow. But Viswamitra replied that they could only come to Mithila on the way to Himalayas.

Then Rama, Lakshmana with Viswamitra left Siddhshrama and went North. They reached river Senai and rested there. Viswamitra described his family lineage to Rama and thus they spent the night talking about the Kusa Vamsa. Then they started on their journey and reached river Ganga, bathed and performed 'Homams' and ate their food (prasadham ). When they were resting, Rama expressed his interest in knowing the story of the river Ganga. Viswamitra obliged him by reciting the story of Ganga in detail.